organ: the rest of the peripheral moves into El

The speaker and the voice-fetch landed in the previous commit. This is the
remainder of the 939-line Swift program, ported, and the line it draws is
between DEVICE and ARITHMETIC rather than between languages.

Two things stay realizers, because they are the two things El cannot express
as arithmetic: handing a buffer to the DAC and waiting for it to drain
(el_audio_darwin.m), and asking the OS for samples off a mic or frames off a
camera (el_capture_darwin.m). Both are their own translation units declared
in el_runtime.h, never patches to el_runtime.c.

Everything else is El. WAV decode, LPC autocorrelation, Levinson-Durbin at
order 16, formant extraction off the all-pole envelope, source-filter
resynthesis, and the three descriptors are organ_dsp.el. Consent, disclosure
and the scene descriptor are organ.el. Barge-in, yield-or-hold, backchannel
and resume are organ_converse.el.

The organ never learns a word. Codes and phoneme geometry arrive from the
language side; the organ turns them into samples and gets the samples out the
speaker, and runs the same trip in reverse for the senses. No lexicon, no
grapheme-to-phoneme, by design.

Barge-in needed pause/resume and a real DAC position rather than a tick
counter, because "finish the buffer" is not barge-in and a queue holding
three buffers is a third of a second wrong about where it is. An injected
barge also had to fire once rather than stay true, which is otherwise a
livelock the moment a backchannel resumes.

Measured against the Swift on out/mic_room.wav: seconds, rms, peak, zcr,
centroid and F0 agree to every printed digit; formants F1-F5 and bandwidths
B1-B5 are identical. imitate cannot match bit-for-bit because the Swift
excites unvoiced frames with Double.random — two Swift runs correlate 0.957
with each other and El correlates 0.958 with Swift, so the port is as close
to the original as the original is to itself.

Verified end to end: consent fails closed on both locks, real mic capture
(16000 frames), real camera frame (1920x1080 -> 15 numbers), voiceprint,
imitate, hear-imitate, a voice learned by ear and fetched back out of the
engram, and all five converse paths with real audio. The binary contains
zero afplay/Swift strings and spawns no child process while speaking.

.gitignore

@@ -0,0 +1,6 @@
+
+# organ: local device state and its own engram store — never production's
+peripheral/.consent.json
+peripheral/.resume.json
+peripheral/.engram/
+peripheral/organ

lang/runtime/el_audio_darwin.m

@@ -0,0 +1,525 @@
+/* el_audio_darwin.m — the SPEAKER realizer. El's native audio output on Darwin.
+ *
+ * WHY THIS FILE EXISTS.
+ *
+ * Neuron could already turn meaning into samples — the render path in
+ * elp/src/speech.el superposes formant resonances over a glottal source and
+ * produces PCM. What it could not do was make a sound. Every path from those
+ * samples to the air ran outside the language: a 939-line Swift program
+ * (peripheral/src/periph.swift) that shelled out to /usr/bin/afplay. So the
+ * voice was not a capability of El or of Neuron. It was a separate binary
+ * standing next to them, and "speak" meant "ask that binary to speak."
+ *
+ * A speaker is not a language feature the way a string is, but it is exactly
+ * the kind of thing a runtime owns: a device. El already owns the filesystem,
+ * the network, the clock, and a graph. It should own the one output device that
+ * makes it audible. After this file, `speak` is an El operation.
+ *
+ * WHY IT IS A REALIZER AND NOT PURE EL.
+ *
+ * This is the boundary the whole design turns on. Everything ABOVE the sample
+ * buffer is arithmetic and belongs in El: formant geometry, superposition,
+ * envelopes, WAV framing, the voice signature. Everything in this file is the
+ * part that cannot be arithmetic — handing a buffer to CoreAudio and waiting
+ * for the hardware to drain it. There is no way to express "the DAC has now
+ * played these samples" in El, and there should not be. So the split is: El
+ * computes the sound, the realizer emits it, and the realizer is as thin as it
+ * can possibly be — it makes no decisions about content, it has no opinion
+ * about audio, and it cannot synthesize anything.
+ *
+ * The precedent is eg_cosine_batch_strategy_metal_hand.m: a platform-bound
+ * capability compiled as its OWN translation unit, declared in el_runtime.h,
+ * and linked in where the platform supports it. Deliberately NOT a patch to
+ * el_runtime.c — adding a device to El must not mean editing the core runtime,
+ * for the same reason adding a modality must not (see el_runtime.c's realizer
+ * registry: a realizer is resolved by name, so new organs never touch the
+ * middle of the language). el_audio_null.c is the same two entry points for
+ * every platform that is not Darwin, so El code that speaks still links
+ * everywhere and simply reports that it has no speaker.
+ *
+ * WHY AudioQueue AND NOT afplay.
+ *
+ * afplay is a process. Using it means the sound Neuron makes is a file it wrote
+ * and asked something else to open — which forces every utterance through the
+ * disk, cannot start until the whole utterance exists, and puts a fork/exec
+ * between the intent to speak and the sound. AudioQueue takes the samples
+ * directly out of memory. Nothing is written, nothing is spawned, and a caller
+ * that wants to stream can push buffers as it renders them.
+ *
+ * AudioToolbox ships with macOS, so this stays own-core: no cloud, no library
+ * to install, no model. The output is the local speaker and nothing leaves the
+ * machine — there is no network path in this file at all, by construction.
+ */
+
+#import <AudioToolbox/AudioToolbox.h>
+#import <Foundation/Foundation.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include "el_runtime.h"
+
+/* Three buffers is the standard AudioQueue depth: one being played by the
+ * hardware, one queued behind it, one being refilled. Fewer risks a gap on a
+ * busy machine; more only adds latency before the first sound. */
+#define EL_AQ_NBUF   3
+#define EL_AQ_FRAMES 8192
+
+typedef struct {
+    const int16_t* pcm;
+    int64_t        frames;
+    int64_t        pos;
+    volatile int   inflight;   /* buffers CoreAudio still owns */
+    volatile int   drained;    /* set once the last buffer has been played */
+} ElAqState;
+
+/* Called on an AudioQueue-internal thread each time a buffer finishes playing.
+ * Refills and re-enqueues while samples remain; when the source is exhausted it
+ * lets the buffer die and counts it out. `drained` flips only when the queue is
+ * holding nothing, which is what makes the play call synchronous without
+ * clipping the tail — the same reason periph.swift used .dataPlayedBack rather
+ * than treating "consumed" as "heard". */
+static void el_aq_callback(void* userData, AudioQueueRef q, AudioQueueBufferRef buf) {
+    ElAqState* st = (ElAqState*)userData;
+    int64_t remain = st->frames - st->pos;
+    if (remain <= 0) {
+        if (--st->inflight <= 0) st->drained = 1;
+        return;
+    }
+    int64_t n = remain < EL_AQ_FRAMES ? remain : EL_AQ_FRAMES;
+    memcpy(buf->mAudioData, st->pcm + st->pos, (size_t)n * sizeof(int16_t));
+    buf->mAudioDataByteSize = (UInt32)(n * (int64_t)sizeof(int16_t));
+    st->pos += n;
+    if (AudioQueueEnqueueBuffer(q, buf, 0, NULL) != noErr) {
+        if (--st->inflight <= 0) st->drained = 1;
+    }
+}
+
+/* Play a 16-bit mono PCM buffer out the default output device, blocking until
+ * the hardware has actually finished. Returns 1 on success, 0 on any failure —
+ * never throws, never hangs indefinitely. */
+static int el_audio_play_raw(const int16_t* pcm, int64_t frames, int32_t sample_rate) {
+    if (!pcm || frames <= 0 || sample_rate <= 0) return 0;
+
+    AudioStreamBasicDescription fmt;
+    memset(&fmt, 0, sizeof(fmt));
+    fmt.mSampleRate       = (Float64)sample_rate;
+    fmt.mFormatID         = kAudioFormatLinearPCM;
+    fmt.mFormatFlags      = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
+    fmt.mFramesPerPacket  = 1;
+    fmt.mChannelsPerFrame = 1;
+    fmt.mBitsPerChannel   = 16;
+    fmt.mBytesPerFrame    = 2;
+    fmt.mBytesPerPacket   = 2;
+
+    ElAqState st;
+    memset(&st, 0, sizeof(st));
+    st.pcm    = pcm;
+    st.frames = frames;
+
+    AudioQueueRef q = NULL;
+    /* NULL run loop => callbacks arrive on an AudioQueue-internal thread, so
+     * this function can simply wait rather than having to pump a run loop it
+     * does not own. El programs are not required to have one. */
+    if (AudioQueueNewOutput(&fmt, el_aq_callback, &st, NULL, NULL, 0, &q) != noErr || !q) {
+        return 0;
+    }
+
+    AudioQueueBufferRef bufs[EL_AQ_NBUF];
+    int prepared = 0;
+    for (int i = 0; i < EL_AQ_NBUF; i++) {
+        if (AudioQueueAllocateBuffer(q, EL_AQ_FRAMES * sizeof(int16_t), &bufs[i]) != noErr) break;
+        prepared++;
+    }
+    if (prepared == 0) { AudioQueueDispose(q, true); return 0; }
+
+    /* Prime: fill what we can before starting, so playback begins immediately
+     * rather than after the first underrun. */
+    for (int i = 0; i < prepared; i++) {
+        int64_t remain = st.frames - st.pos;
+        if (remain <= 0) break;
+        int64_t n = remain < EL_AQ_FRAMES ? remain : EL_AQ_FRAMES;
+        memcpy(bufs[i]->mAudioData, st.pcm + st.pos, (size_t)n * sizeof(int16_t));
+        bufs[i]->mAudioDataByteSize = (UInt32)(n * (int64_t)sizeof(int16_t));
+        st.pos += n;
+        if (AudioQueueEnqueueBuffer(q, bufs[i], 0, NULL) != noErr) break;
+        st.inflight++;
+    }
+    if (st.inflight == 0) { AudioQueueDispose(q, true); return 0; }
+
+    if (AudioQueueStart(q, NULL) != noErr) { AudioQueueDispose(q, true); return 0; }
+
+    /* Bound the wait by the material's own duration plus a margin. A speaker
+     * that wedges a program is worse than a speaker that gives up. */
+    double   seconds  = (double)frames / (double)sample_rate;
+    int64_t  max_us   = (int64_t)((seconds + 5.0) * 1000000.0);
+    int64_t  waited   = 0;
+    const int64_t tick = 5000;   /* 5 ms */
+    while (!st.drained && waited < max_us) {
+        usleep((useconds_t)tick);
+        waited += tick;
+    }
+
+    AudioQueueStop(q, true);
+    AudioQueueDispose(q, true);
+    return st.drained ? 1 : 0;
+}
+
+/* ── El entry points ────────────────────────────────────────────────────────
+ * Declared in el_runtime.h; see there for the El-facing contract. */
+
+/* 1 when this build has a real speaker behind it. El code should ask before
+ * speaking so the no-speaker case is a reported condition, not a silence that
+ * looks like success. */
+el_val_t speaker_available(void) {
+    return (el_val_t)1;
+}
+
+el_val_t speaker_name(void) {
+    return EL_STR("coreaudio-audioqueue");
+}
+
+/* Play an El [Int] of 16-bit samples. Values are clamped, not wrapped: a
+ * render that overshoots should distort at the rails the way real clipping
+ * does, rather than invert phase and produce a sound nothing in the signal
+ * chain intended. */
+el_val_t speaker_play_pcm16(el_val_t samples, el_val_t sample_rate) {
+    int64_t n = (int64_t)el_list_len(samples);
+    int32_t sr = (int32_t)sample_rate;
+    if (n <= 0 || sr <= 0) return (el_val_t)0;
+
+    int16_t* pcm = (int16_t*)malloc((size_t)n * sizeof(int16_t));
+    if (!pcm) return (el_val_t)0;
+
+    for (int64_t i = 0; i < n; i++) {
+        int64_t v = (int64_t)el_list_get(samples, (el_val_t)i);
+        if (v >  32767) v =  32767;
+        if (v < -32768) v = -32768;
+        pcm[i] = (int16_t)v;
+    }
+
+    int ok = el_audio_play_raw(pcm, n, sr);
+    free(pcm);
+    return (el_val_t)(ok ? 1 : 0);
+}
+
+/* ── Asynchronous playback ───────────────────────────────────────────────────
+ *
+ * converse needs this and a blocking play cannot give it. Barge-in means
+ * stopping ON THE SPOT when the user starts talking — not at the end of the
+ * current buffer, and certainly not at the end of the utterance. So the async
+ * path keeps one queue alive, reports how far the hardware actually got, and
+ * can be halted mid-buffer.
+ *
+ * `played_frames` is what makes an interrupted utterance resumable at the
+ * sample rather than at the segment: it is the position the DAC reached, not
+ * the position we enqueued to, and those differ by up to the full queue depth.
+ *
+ * One utterance at a time. A second async play stops the first — a mouth that
+ * can say two things at once is not a feature. */
+
+static AudioQueueRef  g_aq          = NULL;
+static ElAqState*     g_aq_state    = NULL;
+static int16_t*       g_aq_pcm      = NULL;
+static int32_t        g_aq_sr       = 0;
+
+static void el_audio_teardown(void) {
+    if (g_aq) {
+        AudioQueueStop(g_aq, true);
+        AudioQueueDispose(g_aq, true);
+        g_aq = NULL;
+    }
+    free(g_aq_pcm);   g_aq_pcm   = NULL;
+    free(g_aq_state); g_aq_state = NULL;
+    g_aq_sr = 0;
+}
+
+el_val_t speaker_play_pcm16_async(el_val_t samples, el_val_t sample_rate) {
+    el_audio_teardown();
+
+    int64_t n  = (int64_t)el_list_len(samples);
+    int32_t sr = (int32_t)sample_rate;
+    if (n <= 0 || sr <= 0) return (el_val_t)0;
+
+    g_aq_pcm = (int16_t*)malloc((size_t)n * sizeof(int16_t));
+    if (!g_aq_pcm) return (el_val_t)0;
+    for (int64_t i = 0; i < n; i++) {
+        int64_t v = (int64_t)el_list_get(samples, (el_val_t)i);
+        if (v >  32767) v =  32767;
+        if (v < -32768) v = -32768;
+        g_aq_pcm[i] = (int16_t)v;
+    }
+
+    g_aq_state = (ElAqState*)calloc(1, sizeof(ElAqState));
+    if (!g_aq_state) { el_audio_teardown(); return (el_val_t)0; }
+    g_aq_state->pcm    = g_aq_pcm;
+    g_aq_state->frames = n;
+    g_aq_sr            = sr;
+
+    AudioStreamBasicDescription fmt;
+    memset(&fmt, 0, sizeof(fmt));
+    fmt.mSampleRate       = (Float64)sr;
+    fmt.mFormatID         = kAudioFormatLinearPCM;
+    fmt.mFormatFlags      = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
+    fmt.mFramesPerPacket  = 1;
+    fmt.mChannelsPerFrame = 1;
+    fmt.mBitsPerChannel   = 16;
+    fmt.mBytesPerFrame    = 2;
+    fmt.mBytesPerPacket   = 2;
+
+    if (AudioQueueNewOutput(&fmt, el_aq_callback, g_aq_state, NULL, NULL, 0, &g_aq) != noErr || !g_aq) {
+        el_audio_teardown();
+        return (el_val_t)0;
+    }
+
+    for (int i = 0; i < EL_AQ_NBUF; i++) {
+        int64_t remain = g_aq_state->frames - g_aq_state->pos;
+        if (remain <= 0) break;
+        AudioQueueBufferRef b = NULL;
+        if (AudioQueueAllocateBuffer(g_aq, EL_AQ_FRAMES * sizeof(int16_t), &b) != noErr) break;
+        int64_t k = remain < EL_AQ_FRAMES ? remain : EL_AQ_FRAMES;
+        memcpy(b->mAudioData, g_aq_state->pcm + g_aq_state->pos, (size_t)k * sizeof(int16_t));
+        b->mAudioDataByteSize = (UInt32)(k * (int64_t)sizeof(int16_t));
+        g_aq_state->pos += k;
+        if (AudioQueueEnqueueBuffer(g_aq, b, 0, NULL) != noErr) break;
+        g_aq_state->inflight++;
+    }
+    if (g_aq_state->inflight == 0) { el_audio_teardown(); return (el_val_t)0; }
+
+    if (AudioQueueStart(g_aq, NULL) != noErr) { el_audio_teardown(); return (el_val_t)0; }
+    return (el_val_t)1;
+}
+
+el_val_t speaker_playing(void) {
+    if (!g_aq || !g_aq_state) return (el_val_t)0;
+    return (el_val_t)(g_aq_state->drained ? 0 : 1);
+}
+
+/* Frames the DAC has actually rendered. AudioQueueGetCurrentTime's mSampleTime
+ * is relative to queue start, which is exactly the "where was I really" figure
+ * a resumable utterance needs. Falls back to the enqueued position if the
+ * timeline is unavailable (it is, briefly, right after start). */
+el_val_t speaker_played_frames(void) {
+    if (!g_aq || !g_aq_state) return (el_val_t)0;
+    AudioTimeStamp ts;
+    memset(&ts, 0, sizeof(ts));
+    Boolean discontinuity = false;
+    if (AudioQueueGetCurrentTime(g_aq, NULL, &ts, &discontinuity) == noErr &&
+        (ts.mFlags & kAudioTimeStampSampleTimeValid)) {
+        int64_t played = (int64_t)ts.mSampleTime;
+        if (played < 0) played = 0;
+        if (played > g_aq_state->frames) played = g_aq_state->frames;
+        return (el_val_t)played;
+    }
+    return (el_val_t)g_aq_state->pos;
+}
+
+/* Pause where we are, keeping the queue and its position intact.
+ *
+ * This is the difference between barge-in and "finish the buffer". The moment
+ * the microphone hears speech, output must stop AT THAT SAMPLE — a listener
+ * experiences even 200ms of continued talking as being talked over. Pause
+ * rather than stop because the interruption might turn out to be a backchannel
+ * ("mm-hm"), and the right response to a backchannel is to carry on as though
+ * nothing happened, which requires the queue to still be exactly where it was.
+ * A stop-and-restart would re-attack the buffer and be audible as a stutter. */
+el_val_t speaker_pause(void) {
+    if (!g_aq) return (el_val_t)0;
+    return (el_val_t)(AudioQueuePause(g_aq) == noErr ? 1 : 0);
+}
+
+el_val_t speaker_resume(void) {
+    if (!g_aq) return (el_val_t)0;
+    return (el_val_t)(AudioQueueStart(g_aq, NULL) == noErr ? 1 : 0);
+}
+
+el_val_t speaker_stop(void) {
+    if (!g_aq) return (el_val_t)0;
+    /* immediate: do NOT let the queue finish what it is holding */
+    AudioQueueStop(g_aq, true);
+    el_audio_teardown();
+    return (el_val_t)1;
+}
+
+/* Decode a 16-bit RIFF/WAVE into a freshly malloc'd mono int16 buffer.
+ * Returns frames, or 0 on any failure; *out is set only on success. Shared by
+ * the blocking and async WAV paths. */
+static int64_t el_wav_load(const char* path, int16_t** out, int32_t* out_sr) {
+    if (!path || !out) return 0;
+    FILE* f = fopen(path, "rb");
+    if (!f) return 0;
+    if (fseek(f, 0, SEEK_END) != 0) { fclose(f); return 0; }
+    long size = ftell(f);
+    if (size <= 44) { fclose(f); return 0; }
+    rewind(f);
+    unsigned char* d = (unsigned char*)malloc((size_t)size);
+    if (!d) { fclose(f); return 0; }
+    size_t got = fread(d, 1, (size_t)size, f);
+    fclose(f);
+    if (got != (size_t)size) { free(d); return 0; }
+    if (memcmp(d, "RIFF", 4) != 0 || memcmp(d + 8, "WAVE", 4) != 0) { free(d); return 0; }
+
+    int32_t sr = 0, channels = 0, bits = 0;
+    long dataOff = -1, dataLen = 0, o = 12;
+    /* Chunk-walk rather than assuming fmt-then-data at fixed offsets: recorders
+     * routinely interleave JUNK/FLLR padding, and a fixed-offset parser reads
+     * padding as audio. */
+    while (o + 8 <= size) {
+        long sz = (long)d[o+4] | ((long)d[o+5] << 8) | ((long)d[o+6] << 16) | ((long)d[o+7] << 24);
+        if (sz < 0) break;
+        if (memcmp(d + o, "fmt ", 4) == 0 && o + 24 <= size) {
+            channels = (int32_t)(d[o+10] | (d[o+11] << 8));
+            sr       = (int32_t)((long)d[o+12] | ((long)d[o+13] << 8) | ((long)d[o+14] << 16) | ((long)d[o+15] << 24));
+            bits     = (int32_t)(d[o+22] | (d[o+23] << 8));
+        } else if (memcmp(d + o, "data", 4) == 0) {
+            dataOff = o + 8;
+            dataLen = sz;
+            if (dataOff + dataLen > size) dataLen = size - dataOff;
+        }
+        o += 8 + sz + (sz & 1);
+    }
+    if (dataOff < 0 || sr <= 0 || bits != 16 || channels < 1 || dataLen <= 0) { free(d); return 0; }
+
+    long frames = dataLen / (2 * channels);
+    int16_t* pcm = (int16_t*)malloc((size_t)frames * sizeof(int16_t));
+    if (!pcm) { free(d); return 0; }
+    for (long i = 0; i < frames; i++) {
+        long b = dataOff + i * 2 * channels;
+        pcm[i] = (int16_t)((unsigned)d[b] | ((unsigned)d[b+1] << 8));
+    }
+    free(d);
+    *out = pcm;
+    if (out_sr) *out_sr = sr;
+    return (int64_t)frames;
+}
+
+/* Async WAV playback. converse speaks PRE-RENDERED segments and must keep
+ * listening while it does, so it needs the file on the queue without blocking
+ * and needs to be able to stop it mid-buffer. Going through the file rather
+ * than an El [Int] also avoids marshalling a million-element list per segment
+ * for audio the caller never intends to look at. */
+el_val_t speaker_play_wav_async(el_val_t path) {
+    const char* p = EL_CSTR(path);
+    if (!p) return (el_val_t)0;
+
+    el_audio_teardown();
+
+    int32_t  sr = 0;
+    int16_t* pcm = NULL;
+    int64_t  frames = el_wav_load(p, &pcm, &sr);
+    if (frames <= 0 || !pcm) { free(pcm); return (el_val_t)0; }
+
+    g_aq_pcm   = pcm;
+    g_aq_sr    = sr;
+    g_aq_state = (ElAqState*)calloc(1, sizeof(ElAqState));
+    if (!g_aq_state) { el_audio_teardown(); return (el_val_t)0; }
+    g_aq_state->pcm    = g_aq_pcm;
+    g_aq_state->frames = frames;
+
+    AudioStreamBasicDescription fmt;
+    memset(&fmt, 0, sizeof(fmt));
+    fmt.mSampleRate       = (Float64)sr;
+    fmt.mFormatID         = kAudioFormatLinearPCM;
+    fmt.mFormatFlags      = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
+    fmt.mFramesPerPacket  = 1;
+    fmt.mChannelsPerFrame = 1;
+    fmt.mBitsPerChannel   = 16;
+    fmt.mBytesPerFrame    = 2;
+    fmt.mBytesPerPacket   = 2;
+
+    if (AudioQueueNewOutput(&fmt, el_aq_callback, g_aq_state, NULL, NULL, 0, &g_aq) != noErr || !g_aq) {
+        el_audio_teardown();
+        return (el_val_t)0;
+    }
+    for (int i = 0; i < EL_AQ_NBUF; i++) {
+        int64_t remain = g_aq_state->frames - g_aq_state->pos;
+        if (remain <= 0) break;
+        AudioQueueBufferRef b = NULL;
+        if (AudioQueueAllocateBuffer(g_aq, EL_AQ_FRAMES * sizeof(int16_t), &b) != noErr) break;
+        int64_t k = remain < EL_AQ_FRAMES ? remain : EL_AQ_FRAMES;
+        memcpy(b->mAudioData, g_aq_state->pcm + g_aq_state->pos, (size_t)k * sizeof(int16_t));
+        b->mAudioDataByteSize = (UInt32)(k * (int64_t)sizeof(int16_t));
+        g_aq_state->pos += k;
+        if (AudioQueueEnqueueBuffer(g_aq, b, 0, NULL) != noErr) break;
+        g_aq_state->inflight++;
+    }
+    if (g_aq_state->inflight == 0) { el_audio_teardown(); return (el_val_t)0; }
+    if (AudioQueueStart(g_aq, NULL) != noErr) { el_audio_teardown(); return (el_val_t)0; }
+    return (el_val_t)1;
+}
+
+/* Total frames and sample rate of a WAV, without playing it — wav-info, and the
+ * duration converse needs to compute progress through a segment. */
+el_val_t wav_frames(el_val_t path) {
+    const char* p = EL_CSTR(path);
+    int16_t* pcm = NULL; int32_t sr = 0;
+    int64_t n = el_wav_load(p, &pcm, &sr);
+    free(pcm);
+    return (el_val_t)n;
+}
+
+el_val_t wav_rate(el_val_t path) {
+    const char* p = EL_CSTR(path);
+    int16_t* pcm = NULL; int32_t sr = 0;
+    int64_t n = el_wav_load(p, &pcm, &sr);
+    free(pcm);
+    return (el_val_t)(n > 0 ? sr : 0);
+}
+
+/* Play a 16-bit mono RIFF/WAVE file. Present because the render already knows
+ * how to write a WAV and a caller may reasonably want to hear one back without
+ * re-rendering it; the parse is deliberately minimal and chunk-walking, so the
+ * JUNK/FLLR padding that recorders emit does not defeat it. */
+el_val_t speaker_play_wav(el_val_t path) {
+    const char* p = EL_CSTR(path);
+    if (!p) return (el_val_t)0;
+    FILE* f = fopen(p, "rb");
+    if (!f) return (el_val_t)0;
+
+    if (fseek(f, 0, SEEK_END) != 0) { fclose(f); return (el_val_t)0; }
+    long size = ftell(f);
+    if (size <= 44) { fclose(f); return (el_val_t)0; }
+    rewind(f);
+
+    unsigned char* d = (unsigned char*)malloc((size_t)size);
+    if (!d) { fclose(f); return (el_val_t)0; }
+    size_t got = fread(d, 1, (size_t)size, f);
+    fclose(f);
+    if (got != (size_t)size) { free(d); return (el_val_t)0; }
+
+    if (memcmp(d, "RIFF", 4) != 0 || memcmp(d + 8, "WAVE", 4) != 0) { free(d); return (el_val_t)0; }
+
+    int32_t sr = 0, channels = 0, bits = 0;
+    long dataOff = -1, dataLen = 0;
+    long o = 12;
+    while (o + 8 <= size) {
+        long sz = (long)d[o+4] | ((long)d[o+5] << 8) | ((long)d[o+6] << 16) | ((long)d[o+7] << 24);
+        if (sz < 0) break;
+        if (memcmp(d + o, "fmt ", 4) == 0 && o + 24 <= size) {
+            channels = (int32_t)(d[o+10] | (d[o+11] << 8));
+            sr       = (int32_t)((long)d[o+12] | ((long)d[o+13] << 8) | ((long)d[o+14] << 16) | ((long)d[o+15] << 24));
+            bits     = (int32_t)(d[o+22] | (d[o+23] << 8));
+        } else if (memcmp(d + o, "data", 4) == 0) {
+            dataOff = o + 8;
+            dataLen = sz;
+            if (dataOff + dataLen > size) dataLen = size - dataOff;
+        }
+        o += 8 + sz + (sz & 1);
+    }
+    if (dataOff < 0 || sr <= 0 || bits != 16 || channels < 1 || dataLen <= 0) { free(d); return (el_val_t)0; }
+
+    long frames = dataLen / (2 * channels);
+    int16_t* pcm = (int16_t*)malloc((size_t)frames * sizeof(int16_t));
+    if (!pcm) { free(d); return (el_val_t)0; }
+    /* Take channel 0; the organ is mono by design and downmixing would be an
+     * opinion about content this layer is not entitled to have. */
+    for (long i = 0; i < frames; i++) {
+        long b = dataOff + i * 2 * channels;
+        pcm[i] = (int16_t)((unsigned)d[b] | ((unsigned)d[b+1] << 8));
+    }
+    free(d);
+
+    int ok = el_audio_play_raw(pcm, frames, sr);
+    free(pcm);
+    return (el_val_t)(ok ? 1 : 0);
+}

lang/runtime/el_capture_darwin.m

@@ -0,0 +1,841 @@
+/* el_capture_darwin.m — the MICROPHONE and CAMERA realizers. El's afferent
+ * organ on Darwin: the two entry points through which the world gets in.
+ *
+ * WHY THIS FILE EXISTS, AND WHY IT IS A REALIZER RATHER THAN PURE EL.
+ *
+ * el_audio_darwin.m argued the efferent half of this: El can compute a sound
+ * but it cannot make one, because "the DAC has now played these samples" is not
+ * a fact any amount of arithmetic can produce. This file is the same argument
+ * run backwards. El can compute *about* a sound — it can window it, take its
+ * autocorrelation, run Levinson-Durbin over that, find the formant peaks in the
+ * resulting all-pole envelope, and hand back a voiceprint — but it cannot ASK.
+ * There is no expression in El, and there must not be, whose value is "the next
+ * 1024 frames the microphone hears" or "what the camera is pointed at right
+ * now." Those are not computed; they are *requested*, from an operating system
+ * that owns the device, mediates consent for it, and delivers the answer on a
+ * thread of its choosing whenever it feels like it. Asking is the one primitive
+ * operation here. Everything else in this file is bookkeeping around the ask.
+ *
+ * So the line is drawn exactly where el_audio_darwin.m drew it, at the sample
+ * buffer, and it is drawn on purpose:
+ *
+ *   BELOW the line (here): open the device, honour the OS permission gate,
+ *   install a tap or a frame delegate, convert whatever the hardware happens to
+ *   emit into the one shape El asked for, and hand it up. No opinions about
+ *   content. No analysis. No decisions.
+ *
+ *   ABOVE the line (El): energy, zero-crossing rate, spectral centroid, F0 by
+ *   autocorrelation, LPC, formants F1-F5, the compact descriptors, the
+ *   scene-geometry grid, the yield-or-hold turn-taking decision. All of it is
+ *   arithmetic over a buffer, all of it belongs in El, and none of it appears
+ *   below. The reference this file ports — peripheral/src/periph.swift — held
+ *   both halves, and that was the problem worth fixing: the descriptors were
+ *   trapped in a 939-line binary standing next to the language instead of being
+ *   written in it. Porting the *whole* of periph.swift down here would have
+ *   reproduced that mistake in C. Only the ask came down.
+ *
+ * The precedent for the file's SHAPE is eg_cosine_batch_strategy_metal_hand.m:
+ * a platform-bound capability compiled as its own translation unit, declared in
+ * el_runtime.h, linked in where the platform supports it, and deliberately NOT
+ * a patch to the middle of el_runtime.c. Acquiring a device must not mean
+ * editing the language, for the same reason acquiring a modality must not (see
+ * the realizer registry: organs are resolved by name). el_peripheral_null.c is
+ * the same entry points everywhere else, so El code that listens still links on
+ * every platform and merely reports having no ear.
+ *
+ * FAIL CLOSED, ALWAYS.
+ *
+ * A capture path that returns plausible-looking zeros when it was denied is
+ * worse than one that returns nothing, because the caller cannot tell the
+ * difference between a silent room and a refused microphone. Every entry point
+ * here checks AVCaptureDevice's authorization status BEFORE touching hardware
+ * and returns the empty value — an empty list, a 0 map — on anything short of
+ * .authorized. mic_available() and camera_available() report that state WITHOUT
+ * prompting, so El can ask "may I?" without the act of asking being a prompt.
+ *
+ * NEVER HANG.
+ *
+ * Every wait in this file is bounded: 30s on a permission prompt (the user has
+ * to walk to the dialog), seconds+5 on a capture of `seconds`, 10s on a camera
+ * frame. An organ that wedges the program holding it is not an organ, it is a
+ * fault. Every path also tears the device down on the way out, including the
+ * failure paths, so a timed-out capture does not leave the mic light on.
+ *
+ * OWN-CORE AND LOCAL BY CONSTRUCTION.
+ *
+ * AVFoundation, CoreVideo, CoreGraphics and ImageIO ship with macOS. There is
+ * no third-party library here, no model, and — the part that matters — no
+ * network path of any kind. Samples and pixels move from local hardware into an
+ * El value and stop. periph.swift had a URLSession in it; this file has no
+ * socket, no URL, and nothing that could grow one without being obvious in
+ * review. Consent is enforced above this layer in El and below it by the OS;
+ * this layer's whole contribution to that is refusing to proceed.
+ *
+ * DISCLOSURE.
+ *
+ * Every actual device touch writes one line to stderr and flushes it, before
+ * the device opens. stderr and not stdout: a program that announces "I am about
+ * to open the microphone" on stdout has corrupted its own output, and the
+ * caller must be able to separate the answer from how it was obtained. One line
+ * per touch, no more — a disclosure rail that spams is a rail people learn to
+ * ignore.
+ */
+
+#if defined(__APPLE__)
+
+#import <Foundation/Foundation.h>
+#import <AVFoundation/AVFoundation.h>
+#import <CoreMedia/CoreMedia.h>
+#import <CoreVideo/CoreVideo.h>
+#import <CoreGraphics/CoreGraphics.h>
+#import <ImageIO/ImageIO.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include "el_runtime.h"
+
+/* ── Disclosure ──────────────────────────────────────────────────────────────
+ * One flushed line per real device touch, on stderr. Flushed rather than
+ * buffered so the line reaches the terminal BEFORE the mic light comes on
+ * rather than whenever the buffer happens to drain. */
+static void el_cap_disclose(const char* what) {
+    fprintf(stderr, "  [peripheral] %s\n", what);
+    fflush(stderr);
+}
+
+/* ── Permission ──────────────────────────────────────────────────────────────
+ * authorizationStatus is a pure read of the TCC database: it never prompts and
+ * never blocks, which is what lets mic_available()/camera_available() answer
+ * honestly without the question itself becoming an event. requestAccess DOES
+ * prompt, so it lives behind its own entry point and nothing calls it
+ * implicitly. */
+
+static int el_cap_authorized(AVMediaType media) {
+    @try {
+        return [AVCaptureDevice authorizationStatusForMediaType:media]
+               == AVAuthorizationStatusAuthorized ? 1 : 0;
+    } @catch (NSException* e) {
+        (void)e;
+        return 0;
+    }
+}
+
+static int el_cap_device_present(AVMediaType media) {
+    @try {
+        return [AVCaptureDevice defaultDeviceWithMediaType:media] != nil ? 1 : 0;
+    } @catch (NSException* e) {
+        (void)e;
+        return 0;
+    }
+}
+
+/* Prompt once and wait, bounded. 30 seconds is the same budget periph.swift
+ * used: long enough for a human to notice a dialog and decide, short enough
+ * that an unattended run fails rather than parks forever. A timeout is reported
+ * as "not granted", which is the safe reading — we genuinely do not know that
+ * it was. */
+static int el_cap_request(AVMediaType media) {
+    __block int granted = 0;
+    dispatch_semaphore_t sem = dispatch_semaphore_create(0);
+    @try {
+        [AVCaptureDevice requestAccessForMediaType:media
+                                 completionHandler:^(BOOL ok) {
+            granted = ok ? 1 : 0;
+            dispatch_semaphore_signal(sem);
+        }];
+    } @catch (NSException* e) {
+        (void)e;
+        return 0;
+    }
+    if (dispatch_semaphore_wait(sem,
+            dispatch_time(DISPATCH_TIME_NOW, (int64_t)(30 * NSEC_PER_SEC))) != 0) {
+        return 0;   /* timed out — treat as refused */
+    }
+    return granted;
+}
+
+/* ════════════════════════════════════════════════════════════════════════════
+ * MICROPHONE — one-shot capture
+ * ══════════════════════════════════════════════════════════════════════════ */
+
+/* The sink the tap block writes into. An object rather than a static so two
+ * captures can never share state, and so ARC keeps it alive for exactly as long
+ * as the block that captured it. The lock is real, not decorative: the tap runs
+ * on an AVAudioEngine-internal thread and the waiter runs on the caller's. */
+@interface ElCapMicSink : NSObject
+@property (nonatomic, strong) NSMutableData* pcm;
+@property (nonatomic, strong) NSLock*        lock;
+@end
+
+@implementation ElCapMicSink
+- (instancetype)init {
+    self = [super init];
+    if (self) {
+        _pcm  = [NSMutableData data];
+        _lock = [[NSLock alloc] init];
+    }
+    return self;
+}
+@end
+
+/* Capture `seconds` of mono 16-bit PCM at `sample_rate`.
+ *
+ * The hardware format is NOT assumed. A built-in mic will typically hand back
+ * float32 at 44.1 or 48 kHz, an aggregate device may be 8 channels at 96 kHz,
+ * and a caller asking for 16 kHz mono (which is what the formant path wants)
+ * gets 16 kHz mono either way. AVAudioConverter does the rate conversion and
+ * the downmix; doing it by hand would mean writing a resampler in the one file
+ * that is supposed to contain no arithmetic.
+ *
+ * The converter is built ONCE, outside the tap, because a sample-rate converter
+ * carries filter state across buffers — rebuilding it per callback would put a
+ * discontinuity at every buffer boundary, which is audible and which would then
+ * show up in El's spectral descriptors as energy that was never in the room. */
+el_val_t mic_capture_pcm16(el_val_t seconds, el_val_t sample_rate) {
+    el_val_t empty = el_list_empty();
+
+    if (!el_cap_authorized(AVMediaTypeAudio)) return empty;
+
+    int64_t secs = (int64_t)seconds;
+    int64_t sr   = (int64_t)sample_rate;
+    if (secs <= 0 || sr <= 0) return empty;
+    /* Bound the ask. A caller that asks for a year of audio has made a mistake,
+     * and honouring it would mean an unkillable capture and an OOM. */
+    if (secs > 300)    secs = 300;
+    if (sr   > 384000) sr   = 384000;
+
+    __block AVAudioEngine* engine = nil;
+    AVAudioInputNode*      input  = nil;
+    AVAudioFormat*         hwFmt  = nil;
+    int                    tapped = 0;
+
+    @try {
+        engine = [[AVAudioEngine alloc] init];
+        input  = [engine inputNode];
+        hwFmt  = [input inputFormatForBus:0];
+    } @catch (NSException* e) {
+        (void)e;
+        return empty;
+    }
+    if (!input || !hwFmt || hwFmt.sampleRate <= 0 || hwFmt.channelCount == 0) {
+        return empty;
+    }
+
+    /* Preferred target: mono int16 at the requested rate. If the converter
+     * refuses that pairing (some exotic input layouts will not downmix), fall
+     * back to keeping the hardware's channel count and taking channel 0 on the
+     * way out — the organ is mono by design and inventing a downmix here would
+     * be an opinion about content this layer is not entitled to have. */
+    AVAudioFormat* outFmt =
+        [[AVAudioFormat alloc] initWithCommonFormat:AVAudioPCMFormatInt16
+                                         sampleRate:(double)sr
+                                           channels:1
+                                        interleaved:YES];
+    AVAudioConverter* conv = outFmt ? [[AVAudioConverter alloc] initFromFormat:hwFmt
+                                                                     toFormat:outFmt] : nil;
+    AVAudioChannelCount outCh = 1;
+    if (!conv) {
+        outFmt = [[AVAudioFormat alloc] initWithCommonFormat:AVAudioPCMFormatInt16
+                                                  sampleRate:(double)sr
+                                                    channels:hwFmt.channelCount
+                                                 interleaved:YES];
+        conv   = outFmt ? [[AVAudioConverter alloc] initFromFormat:hwFmt toFormat:outFmt] : nil;
+        outCh  = hwFmt.channelCount;
+    }
+    if (!conv || !outFmt) return empty;
+
+    ElCapMicSink* sink = [[ElCapMicSink alloc] init];
+    const int64_t want = secs * sr;          /* frames we are waiting for */
+
+    {
+        char msg[192];
+        snprintf(msg, sizeof(msg),
+                 "MIC: opening the microphone for %llds -> %lld Hz mono PCM "
+                 "(local, never egresses).", (long long)secs, (long long)sr);
+        el_cap_disclose(msg);
+    }
+
+    const double ratio = (double)sr / hwFmt.sampleRate;
+
+    @try {
+        [input installTapOnBus:0
+                    bufferSize:4096
+                        format:hwFmt
+                         block:^(AVAudioPCMBuffer* _Nonnull buf, AVAudioTime* _Nonnull when) {
+            (void)when;
+            if (!buf || buf.frameLength == 0) return;
+
+            AVAudioFrameCount cap =
+                (AVAudioFrameCount)((double)buf.frameLength * ratio) + 1024;
+            AVAudioPCMBuffer* out =
+                [[AVAudioPCMBuffer alloc] initWithPCMFormat:outFmt frameCapacity:cap];
+            if (!out) return;
+
+            __block BOOL fed = NO;
+            AVAudioConverterInputBlock feed =
+                ^AVAudioBuffer* _Nullable (AVAudioPacketCount need,
+                                           AVAudioConverterInputStatus* _Nonnull status) {
+                (void)need;
+                if (fed) { *status = AVAudioConverterInputStatus_NoDataNow; return nil; }
+                fed = YES;
+                *status = AVAudioConverterInputStatus_HaveData;
+                return buf;
+            };
+
+            NSError* err = nil;
+            AVAudioConverterOutputStatus st =
+                [conv convertToBuffer:out error:&err withInputFromBlock:feed];
+            if (st == AVAudioConverterOutputStatus_Error || out.frameLength == 0) return;
+
+            const int16_t* src = out.int16ChannelData ? out.int16ChannelData[0] : NULL;
+            if (!src) return;
+
+            NSUInteger n = (NSUInteger)out.frameLength;
+            [sink.lock lock];
+            if (outCh == 1) {
+                [sink.pcm appendBytes:src length:n * sizeof(int16_t)];
+            } else {
+                /* Interleaved: stride to channel 0. */
+                for (NSUInteger i = 0; i < n; i++) {
+                    int16_t v = src[i * outCh];
+                    [sink.pcm appendBytes:&v length:sizeof(int16_t)];
+                }
+            }
+            [sink.lock unlock];
+        }];
+        tapped = 1;
+
+        [engine prepare];
+        NSError* startErr = nil;
+        if (![engine startAndReturnError:&startErr]) {
+            [input removeTapOnBus:0];
+            return empty;
+        }
+    } @catch (NSException* e) {
+        (void)e;
+        @try { if (tapped) [input removeTapOnBus:0]; } @catch (NSException* e2) { (void)e2; }
+        @try { [engine stop]; } @catch (NSException* e2) { (void)e2; }
+        return empty;
+    }
+
+    /* Wait for `want` frames, bounded by the material's own duration plus a
+     * margin. A device that stops producing must not become a hang. */
+    const int64_t deadline_us = (secs + 5) * 1000000;
+    int64_t       waited_us   = 0;
+    const int64_t tick_us     = 5000;
+    for (;;) {
+        [sink.lock lock];
+        int64_t have = (int64_t)([sink.pcm length] / sizeof(int16_t));
+        [sink.lock unlock];
+        if (have >= want || waited_us >= deadline_us) break;
+        usleep((useconds_t)tick_us);
+        waited_us += tick_us;
+    }
+
+    @try { [input removeTapOnBus:0]; } @catch (NSException* e) { (void)e; }
+    @try { [engine stop]; }           @catch (NSException* e) { (void)e; }
+    engine = nil;
+
+    /* Hand up exactly what was asked for, or everything we got if the device
+     * came up short. Never padded: silence we invented is indistinguishable
+     * from silence we heard, and El has no way to tell them apart afterwards. */
+    [sink.lock lock];
+    int64_t have = (int64_t)([sink.pcm length] / sizeof(int16_t));
+    int64_t n    = have < want ? have : want;
+    const int16_t* pcm = (const int16_t*)[sink.pcm bytes];
+    el_val_t list = empty;
+    for (int64_t i = 0; i < n; i++) {
+        list = el_list_append(list, (el_val_t)(int64_t)pcm[i]);
+    }
+    [sink.lock unlock];
+
+    return list;
+}
+
+el_val_t mic_available(void) {
+    if (!el_cap_authorized(AVMediaTypeAudio)) return (el_val_t)0;
+    return (el_val_t)(el_cap_device_present(AVMediaTypeAudio) ? 1 : 0);
+}
+
+el_val_t mic_request_access(void) {
+    return (el_val_t)(el_cap_request(AVMediaTypeAudio) ? 1 : 0);
+}
+
+/* ════════════════════════════════════════════════════════════════════════════
+ * MICROPHONE — live monitor (the full-duplex ear)
+ *
+ * converse needs to keep listening WHILE it speaks, which means the mic is open
+ * at the same time as the speaker. In a real room that is a feedback path:
+ * without cancellation Neuron hears its own voice, decides someone is talking,
+ * and barges in on itself. setVoiceProcessingEnabled: hands the input node to
+ * the OS voice-processing unit, which subtracts the known output signal from
+ * the input — the single thing that makes barge-in work outside a headset.
+ *
+ * It is not always available (some aggregate and virtual devices refuse it), so
+ * failure to enable it is reported as a DISTINCT return value (2) rather than
+ * folded into success. The caller needs to know, because the correct response
+ * is to raise the VAD floor, and a caller that thinks AEC is on will set that
+ * floor far too low.
+ *
+ * The tap keeps only a running short-window RMS in a static behind a mutex.
+ * Deliberately not a queue of samples: this path is polled at ~50 Hz by a loop
+ * that only ever asks "is someone talking", and buffering audio nobody reads
+ * would be an unbounded allocation in the middle of a conversation.
+ * ══════════════════════════════════════════════════════════════════════════ */
+
+static AVAudioEngine*   g_mon_engine = nil;
+static int              g_mon_running = 0;
+static int              g_mon_code = 0;         /* what the successful start reported */
+static double           g_mon_rms = 0.0;
+static pthread_mutex_t  g_mon_lock = PTHREAD_MUTEX_INITIALIZER;
+
+el_val_t mic_monitor_start(void) {
+    /* Idempotent, and it re-reports the ORIGINAL code rather than a bare 1: a
+     * caller that starts twice must not be told AEC is on when the first start
+     * already discovered it was not. */
+    if (g_mon_running) return (el_val_t)g_mon_code;
+    if (!el_cap_authorized(AVMediaTypeAudio)) return (el_val_t)0;
+
+    AVAudioEngine*    engine = nil;
+    AVAudioInputNode* input  = nil;
+    AVAudioFormat*    fmt    = nil;
+    int               aec    = 0;
+    int               tapped = 0;
+
+    @try {
+        engine = [[AVAudioEngine alloc] init];
+        input  = [engine inputNode];
+    } @catch (NSException* e) {
+        (void)e;
+        return (el_val_t)0;
+    }
+    if (!input) return (el_val_t)0;
+
+    /* Enable AEC BEFORE reading the format: the voice-processing unit imposes
+     * its own input format, and a tap installed with the pre-VP format would be
+     * rejected at start. */
+    @try {
+        NSError* vpErr = nil;
+        if ([input respondsToSelector:@selector(setVoiceProcessingEnabled:error:)]) {
+            aec = [input setVoiceProcessingEnabled:YES error:&vpErr] ? 1 : 0;
+        }
+    } @catch (NSException* e) {
+        (void)e;
+        aec = 0;
+    }
+
+    @try {
+        fmt = [input inputFormatForBus:0];
+    } @catch (NSException* e) {
+        (void)e;
+        return (el_val_t)0;
+    }
+    if (!fmt || fmt.sampleRate <= 0 || fmt.channelCount == 0) return (el_val_t)0;
+
+    el_cap_disclose(aec
+        ? "MIC: opening the microphone for live monitoring, echo-cancelled (local)."
+        : "MIC: opening the microphone for live monitoring, NO echo cancellation (local).");
+
+    @try {
+        [input installTapOnBus:0
+                    bufferSize:1024
+                        format:fmt
+                    block:^(AVAudioPCMBuffer* _Nonnull buf, AVAudioTime* _Nonnull when) {
+            (void)when;
+            if (!buf) return;
+            AVAudioFrameCount n = buf.frameLength;
+            if (n == 0) return;
+
+            double sum = 0.0;
+            /* Whatever the VP unit hands back — float32 is the norm, int16 and
+             * int32 are possible on odd hardware — normalise to -1..1 so the
+             * Float El sees means the same thing on every device. */
+            if (buf.floatChannelData) {
+                const float* ch = buf.floatChannelData[0];
+                for (AVAudioFrameCount i = 0; i < n; i++) sum += (double)ch[i] * (double)ch[i];
+            } else if (buf.int16ChannelData) {
+                const int16_t* ch = buf.int16ChannelData[0];
+                for (AVAudioFrameCount i = 0; i < n; i++) {
+                    double v = (double)ch[i] / 32768.0;
+                    sum += v * v;
+                }
+            } else if (buf.int32ChannelData) {
+                const int32_t* ch = buf.int32ChannelData[0];
+                for (AVAudioFrameCount i = 0; i < n; i++) {
+                    double v = (double)ch[i] / 2147483648.0;
+                    sum += v * v;
+                }
+            } else {
+                return;
+            }
+
+            double rms = sqrt(sum / (double)n);
+            if (rms < 0.0) rms = 0.0;
+            if (rms > 1.0) rms = 1.0;
+
+            pthread_mutex_lock(&g_mon_lock);
+            g_mon_rms = rms;
+            pthread_mutex_unlock(&g_mon_lock);
+        }];
+        tapped = 1;
+
+        [engine prepare];
+        NSError* startErr = nil;
+        if (![engine startAndReturnError:&startErr]) {
+            [input removeTapOnBus:0];
+            return (el_val_t)0;
+        }
+    } @catch (NSException* e) {
+        (void)e;
+        @try { if (tapped) [input removeTapOnBus:0]; } @catch (NSException* e2) { (void)e2; }
+        @try { [engine stop]; } @catch (NSException* e2) { (void)e2; }
+        return (el_val_t)0;
+    }
+
+    pthread_mutex_lock(&g_mon_lock);
+    g_mon_rms = 0.0;
+    pthread_mutex_unlock(&g_mon_lock);
+
+    g_mon_engine  = engine;
+    g_mon_running = 1;
+    g_mon_code    = aec ? 1 : 2;
+    return (el_val_t)g_mon_code;
+}
+
+/* Float in 0..1. Reads the last window the tap computed; never blocks on the
+ * audio thread beyond the mutex, because this is polled inside a turn-taking
+ * loop where a stall IS a missed barge-in. */
+el_val_t mic_monitor_rms(void) {
+    double rms = 0.0;
+    pthread_mutex_lock(&g_mon_lock);
+    rms = g_mon_rms;
+    pthread_mutex_unlock(&g_mon_lock);
+    return el_from_float(rms);
+}
+
+el_val_t mic_monitor_stop(void) {
+    AVAudioEngine* engine = g_mon_engine;
+    g_mon_engine  = nil;
+    g_mon_running = 0;
+    g_mon_code    = 0;
+
+    if (engine) {
+        @try { [[engine inputNode] removeTapOnBus:0]; } @catch (NSException* e) { (void)e; }
+        @try { [engine stop]; }                        @catch (NSException* e) { (void)e; }
+    }
+    pthread_mutex_lock(&g_mon_lock);
+    g_mon_rms = 0.0;
+    pthread_mutex_unlock(&g_mon_lock);
+    return (el_val_t)1;
+}
+
+/* ════════════════════════════════════════════════════════════════════════════
+ * CAMERA
+ * ══════════════════════════════════════════════════════════════════════════ */
+
+static void el_cap_free_bitmap(void* info, const void* data, size_t size) {
+    (void)info; (void)size;
+    free((void*)data);
+}
+
+/* CVPixelBuffer -> CGImage, own-core, no CoreImage.
+ *
+ * The output is pinned to 32BGRA at the AVCaptureVideoDataOutput (see below)
+ * precisely so this conversion can be a memcpy and a CGImageCreate. The
+ * alternative — accepting the camera's native 2vuy/420v and colour-converting
+ * here — would mean either pulling in CoreImage or writing a YUV->RGB matrix in
+ * the file that is supposed to contain no arithmetic. Asking the capture output
+ * for BGRA moves that work into AVFoundation, where it is already written and
+ * already hardware-accelerated.
+ *
+ * The rows are copied out rather than aliased because the CVPixelBuffer is
+ * recycled by the capture session the moment the delegate returns; a CGImage
+ * pointing at it would be pointing at the NEXT frame by the time anyone looked. */
+static CGImageRef el_cap_cgimage_from_pixelbuffer(CVPixelBufferRef pb) {
+    if (!pb) return NULL;
+    if (CVPixelBufferGetPixelFormatType(pb) != kCVPixelFormatType_32BGRA) return NULL;
+    if (CVPixelBufferLockBaseAddress(pb, kCVPixelBufferLock_ReadOnly) != kCVReturnSuccess) return NULL;
+
+    size_t         w       = CVPixelBufferGetWidth(pb);
+    size_t         h       = CVPixelBufferGetHeight(pb);
+    size_t         src_bpr = CVPixelBufferGetBytesPerRow(pb);
+    const uint8_t* base    = (const uint8_t*)CVPixelBufferGetBaseAddress(pb);
+
+    CGImageRef img = NULL;
+    if (base && w > 0 && h > 0 && src_bpr >= w * 4) {
+        size_t   dst_bpr = w * 4;
+        uint8_t* copy    = (uint8_t*)malloc(dst_bpr * h);
+        if (copy) {
+            for (size_t y = 0; y < h; y++) {
+                memcpy(copy + y * dst_bpr, base + y * src_bpr, dst_bpr);
+            }
+            CGDataProviderRef dp =
+                CGDataProviderCreateWithData(NULL, copy, dst_bpr * h, el_cap_free_bitmap);
+            if (dp) {
+                CGColorSpaceRef cs = CGColorSpaceCreateDeviceRGB();
+                if (cs) {
+                    img = CGImageCreate(w, h, 8, 32, dst_bpr, cs,
+                                        (CGBitmapInfo)(kCGBitmapByteOrder32Little |
+                                                       kCGImageAlphaNoneSkipFirst),
+                                        dp, NULL, false, kCGRenderingIntentDefault);
+                    CGColorSpaceRelease(cs);
+                }
+                CGDataProviderRelease(dp);   /* provider owns `copy` from here */
+            } else {
+                free(copy);
+            }
+        }
+    }
+
+    CVPixelBufferUnlockBaseAddress(pb, kCVPixelBufferLock_ReadOnly);
+    return img;
+}
+
+/* The frame delegate. AVCaptureVideoDataOutput is used rather than
+ * AVCapturePhotoOutput for the same reason periph.swift used it: the photo path
+ * wants KVO and a session owned by an app object, and this runs in a plain CLI
+ * process with no run loop it can assume. A data output just calls back.
+ *
+ * The first frames are dropped on purpose. A camera that has just been powered
+ * on is still converging exposure and white balance, and the first frame is
+ * reliably darker and greener than the room. El's scene-geometry descriptors
+ * are brightness and mean-colour statistics, so handing up an unsettled frame
+ * would not produce a slightly worse answer, it would produce a confidently
+ * wrong one. */
+@interface ElCapFrameGrabber : NSObject <AVCaptureVideoDataOutputSampleBufferDelegate> {
+    CGImageRef            _img;
+    int                   _seen;
+    dispatch_semaphore_t  _sem;
+}
+- (dispatch_semaphore_t)sem;
+- (CGImageRef)takeImage;   /* transfers ownership to the caller */
+@end
+
+@implementation ElCapFrameGrabber
+
+- (instancetype)init {
+    self = [super init];
+    if (self) {
+        _img  = NULL;
+        _seen = 0;
+        _sem  = dispatch_semaphore_create(0);
+    }
+    return self;
+}
+
+- (dispatch_semaphore_t)sem { return _sem; }
+
+- (CGImageRef)takeImage {
+    CGImageRef out = _img;
+    _img = NULL;
+    return out;
+}
+
+- (void)dealloc {
+    if (_img) { CGImageRelease(_img); _img = NULL; }
+}
+
+/* Runs on the serial delegate queue, so no lock is needed among callbacks; the
+ * waiter only reads _img after the semaphore has been signalled AND the session
+ * has been stopped, which orders it after the last callback. */
+- (void)captureOutput:(AVCaptureOutput*)output
+didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
+       fromConnection:(AVCaptureConnection*)connection {
+    (void)output; (void)connection;
+    _seen++;
+    if (_img != NULL || _seen < 5) return;      /* let exposure settle */
+
+    CVImageBufferRef pb = CMSampleBufferGetImageBuffer(sampleBuffer);
+    if (!pb) return;
+    CGImageRef img = el_cap_cgimage_from_pixelbuffer(pb);
+    if (!img) return;
+    _img = img;
+    dispatch_semaphore_signal(_sem);
+}
+
+@end
+
+/* Bring the camera up, take exactly one settled frame, put it back down.
+ * Returns a +1 CGImageRef the caller releases, or NULL. Bounded at 10s: a
+ * camera held by another process, or one whose TCC grant was revoked between
+ * the check and the open, must fail rather than park. */
+static CGImageRef el_cap_grab_frame(void) {
+    AVCaptureSession*         session = nil;
+    AVCaptureVideoDataOutput* output  = nil;
+    ElCapFrameGrabber*        grabber = nil;
+    CGImageRef                img     = NULL;
+
+    @try {
+        AVCaptureDevice* dev = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
+        if (!dev) return NULL;
+
+        NSError* err = nil;
+        AVCaptureDeviceInput* in = [AVCaptureDeviceInput deviceInputWithDevice:dev error:&err];
+        if (!in) return NULL;
+
+        session = [[AVCaptureSession alloc] init];
+        session.sessionPreset = AVCaptureSessionPresetPhoto;
+        if (![session canAddInput:in]) return NULL;
+        [session addInput:in];
+
+        output = [[AVCaptureVideoDataOutput alloc] init];
+        output.alwaysDiscardsLateVideoFrames = YES;
+        /* Pin the pixel format so the CGImage conversion above stays a memcpy.
+         * Every macOS capture device advertises 32BGRA. */
+        output.videoSettings = @{ (id)kCVPixelBufferPixelFormatTypeKey :
+                                      @(kCVPixelFormatType_32BGRA) };
+
+        grabber = [[ElCapFrameGrabber alloc] init];
+        dispatch_queue_t q = dispatch_queue_create("el.capture.camera", DISPATCH_QUEUE_SERIAL);
+        [output setSampleBufferDelegate:grabber queue:q];
+
+        if (![session canAddOutput:output]) return NULL;
+        [session addOutput:output];
+
+        el_cap_disclose("CAMERA: opening the camera for one frame (local, never egresses).");
+        [session startRunning];
+    } @catch (NSException* e) {
+        (void)e;
+        @try { [session stopRunning]; } @catch (NSException* e2) { (void)e2; }
+        return NULL;
+    }
+
+    long timed_out = dispatch_semaphore_wait([grabber sem],
+        dispatch_time(DISPATCH_TIME_NOW, (int64_t)(10 * NSEC_PER_SEC)));
+
+    /* Stop first, then detach the delegate, then read. In that order the last
+     * callback has already returned by the time anyone touches the image. */
+    @try { [session stopRunning]; }                        @catch (NSException* e) { (void)e; }
+    @try { [output setSampleBufferDelegate:nil queue:NULL]; } @catch (NSException* e) { (void)e; }
+
+    if (timed_out == 0) img = [grabber takeImage];
+    return img;
+}
+
+el_val_t camera_available(void) {
+    if (!el_cap_authorized(AVMediaTypeVideo)) return (el_val_t)0;
+    return (el_val_t)(el_cap_device_present(AVMediaTypeVideo) ? 1 : 0);
+}
+
+el_val_t camera_request_access(void) {
+    return (el_val_t)(el_cap_request(AVMediaTypeVideo) ? 1 : 0);
+}
+
+/* Longest edge of the grid handed to El. 64 is not a resolution, it is a budget:
+ * a 1920x1080 frame is 6.2 MILLION packed RGB ints, and building that as an El
+ * list would cost more time and memory than everything El then does with it.
+ * The descriptors El computes over this — mean colour, brightness, a 3x3
+ * luminance grid — are region statistics, and region statistics do not get
+ * meaningfully better above a 64-wide grid. The TRUE frame dimensions are
+ * reported separately so nothing downstream has to guess what was thrown away. */
+#define EL_CAP_GRID_MAX 64
+
+/* One frame as Map{width, height, grid_w, grid_h, pixels:[Int]}.
+ *
+ * "pixels" is packed R,G,B with NO alpha — three ints per grid cell, row-major
+ * from the TOP-LEFT. (CGBitmapContext lays its buffer out top row first and
+ * CGContextDrawImage does the flip, so row 0 here is the top of the frame, the
+ * same convention periph.swift's grid indexing assumed.) Alpha is dropped
+ * because a camera frame has none worth carrying and it would inflate the list
+ * by a third to say "opaque" six thousand times. */
+el_val_t camera_capture_rgb(void) {
+    if (!el_cap_authorized(AVMediaTypeVideo)) return (el_val_t)0;
+
+    CGImageRef img = el_cap_grab_frame();
+    if (!img) return (el_val_t)0;
+
+    size_t w = CGImageGetWidth(img);
+    size_t h = CGImageGetHeight(img);
+    if (w == 0 || h == 0) { CGImageRelease(img); return (el_val_t)0; }
+
+    /* Preserve aspect ratio, longest edge capped. */
+    size_t gw = w, gh = h;
+    size_t longest = w > h ? w : h;
+    if (longest > EL_CAP_GRID_MAX) {
+        double s = (double)EL_CAP_GRID_MAX / (double)longest;
+        gw = (size_t)((double)w * s + 0.5);
+        gh = (size_t)((double)h * s + 0.5);
+        if (gw == 0) gw = 1;
+        if (gh == 0) gh = 1;
+    }
+
+    size_t   bpr = gw * 4;
+    uint8_t* buf = (uint8_t*)calloc(1, bpr * gh);
+    if (!buf) { CGImageRelease(img); return (el_val_t)0; }
+
+    CGColorSpaceRef cs = CGColorSpaceCreateDeviceRGB();
+    CGContextRef ctx = cs ? CGBitmapContextCreate(buf, gw, gh, 8, bpr, cs,
+                                                  (CGBitmapInfo)kCGImageAlphaPremultipliedLast)
+                          : NULL;
+    if (cs) CGColorSpaceRelease(cs);
+    if (!ctx) { free(buf); CGImageRelease(img); return (el_val_t)0; }
+
+    /* Nearest-neighbour. This is a decimation for statistics, not a thumbnail
+     * for a human to look at; smoothing would only cost time and blur the very
+     * region boundaries the grid exists to measure. */
+    CGContextSetInterpolationQuality(ctx, kCGInterpolationNone);
+    CGContextDrawImage(ctx, CGRectMake(0, 0, (CGFloat)gw, (CGFloat)gh), img);
+    CGContextRelease(ctx);
+    CGImageRelease(img);
+
+    el_val_t pixels = el_list_empty();
+    for (size_t y = 0; y < gh; y++) {
+        const uint8_t* row = buf + y * bpr;
+        for (size_t x = 0; x < gw; x++) {
+            const uint8_t* p = row + x * 4;   /* RGBA8, premultiplied-last */
+            pixels = el_list_append(pixels, (el_val_t)(int64_t)p[0]);
+            pixels = el_list_append(pixels, (el_val_t)(int64_t)p[1]);
+            pixels = el_list_append(pixels, (el_val_t)(int64_t)p[2]);
+        }
+    }
+    free(buf);
+
+    el_val_t m = el_map_new((el_val_t)0);
+    if (!m) return (el_val_t)0;
+    m = el_map_set(m, EL_STR("width"),  (el_val_t)(int64_t)w);
+    m = el_map_set(m, EL_STR("height"), (el_val_t)(int64_t)h);
+    m = el_map_set(m, EL_STR("grid_w"), (el_val_t)(int64_t)gw);
+    m = el_map_set(m, EL_STR("grid_h"), (el_val_t)(int64_t)gh);
+    m = el_map_set(m, EL_STR("pixels"), pixels);
+    return m;
+}
+
+/* One frame to disk as JPEG, at FULL resolution — the opposite budget from
+ * camera_capture_rgb, and for the opposite reason. A file is not being walked
+ * element-by-element by an interpreter; it costs one ImageIO call and it is the
+ * artefact a human or a later pass will actually look at. The encoder is
+ * ImageIO's because a JPEG encoder is a codec, and re-implementing one in El
+ * would be a large amount of arithmetic that buys nothing: the point of keeping
+ * work in El is the reasoning, not the entropy coding. */
+el_val_t camera_capture_jpeg(el_val_t path) {
+    const char* p = EL_CSTR(path);
+    if (!p || !*p) return (el_val_t)0;
+    if (!el_cap_authorized(AVMediaTypeVideo)) return (el_val_t)0;
+
+    CGImageRef img = el_cap_grab_frame();
+    if (!img) return (el_val_t)0;
+
+    int ok = 0;
+    @autoreleasepool {
+        NSString* ns = [NSString stringWithUTF8String:p];
+        NSURL*    url = ns ? [NSURL fileURLWithPath:ns] : nil;
+        if (url) {
+            CGImageDestinationRef dst =
+                CGImageDestinationCreateWithURL((__bridge CFURLRef)url, CFSTR("public.jpeg"), 1, NULL);
+            if (dst) {
+                CGImageDestinationAddImage(dst, img, NULL);
+                ok = CGImageDestinationFinalize(dst) ? 1 : 0;
+                CFRelease(dst);
+            }
+        }
+    }
+    CGImageRelease(img);
+    return (el_val_t)ok;
+}
+
+#endif /* __APPLE__ */

lang/runtime/el_peripheral_null.c

@@ -0,0 +1,89 @@
+/* el_peripheral_null.c — the no-device build of El's I/O organ.
+ *
+ * Every entry point declared in el_runtime.h's "Peripheral" block, implemented
+ * as an honest refusal. This is what a platform without an El audio/capture
+ * realizer links instead of el_audio_darwin.m + el_capture_darwin.m, so an El
+ * program that speaks or listens still COMPILES AND LINKS everywhere.
+ *
+ * The distinction that matters: these do not pretend. speaker_available() and
+ * mic_available() return 0, and every operation returns its failure sentinel.
+ * A program asking "can I speak here?" gets a truthful no, rather than a
+ * silence it would have to infer something from. Silent success is the failure
+ * mode this whole change exists to eliminate — El spent this entire codebase's
+ * history writing WAV files full of zeros and reporting ok=true, and nobody
+ * caught it because nothing ever said "there is no sound here".
+ *
+ * Compiled INSTEAD OF the Darwin realizers, never alongside them — the symbols
+ * are the same by design, which is the point: the El side never branches on
+ * platform, it branches on speaker_available().
+ */
+
+#include "el_runtime.h"
+
+#if !defined(__APPLE__)
+
+/* ── Speaker ─────────────────────────────────────────────────────────────── */
+
+el_val_t speaker_available(void) { return (el_val_t)0; }
+el_val_t speaker_name(void)      { return EL_STR("none"); }
+
+el_val_t speaker_play_pcm16(el_val_t samples, el_val_t sample_rate) {
+    (void)samples; (void)sample_rate;
+    return (el_val_t)0;
+}
+
+el_val_t speaker_play_wav(el_val_t path) {
+    (void)path;
+    return (el_val_t)0;
+}
+
+el_val_t speaker_play_pcm16_async(el_val_t samples, el_val_t sample_rate) {
+    (void)samples; (void)sample_rate;
+    return (el_val_t)0;
+}
+
+el_val_t speaker_play_wav_async(el_val_t path) {
+    (void)path;
+    return (el_val_t)0;
+}
+
+el_val_t speaker_pause(void)          { return (el_val_t)0; }
+el_val_t speaker_resume(void)         { return (el_val_t)0; }
+el_val_t speaker_playing(void)        { return (el_val_t)0; }
+el_val_t speaker_stop(void)           { return (el_val_t)0; }
+el_val_t speaker_played_frames(void)  { return (el_val_t)0; }
+
+/* WAV geometry is pure parsing and would work fine here, but reporting a
+ * duration for audio this build cannot play would invite a caller to sequence
+ * around a silence. Refuse consistently with the rest of the file. */
+el_val_t wav_frames(el_val_t path) { (void)path; return (el_val_t)0; }
+el_val_t wav_rate(el_val_t path)   { (void)path; return (el_val_t)0; }
+
+/* ── Microphone ──────────────────────────────────────────────────────────── */
+
+el_val_t mic_available(void)       { return (el_val_t)0; }
+el_val_t mic_request_access(void)  { return (el_val_t)0; }
+
+/* Empty list, not 0: the contract says capture returns samples, and a caller
+ * iterating the result must find nothing rather than dereference a non-list. */
+el_val_t mic_capture_pcm16(el_val_t seconds, el_val_t sample_rate) {
+    (void)seconds; (void)sample_rate;
+    return el_list_empty();
+}
+
+el_val_t mic_monitor_start(void) { return (el_val_t)0; }
+el_val_t mic_monitor_rms(void)   { return el_from_float(0.0); }
+el_val_t mic_monitor_stop(void)  { return (el_val_t)0; }
+
+/* ── Camera ──────────────────────────────────────────────────────────────── */
+
+el_val_t camera_available(void)      { return (el_val_t)0; }
+el_val_t camera_request_access(void) { return (el_val_t)0; }
+el_val_t camera_capture_rgb(void)    { return (el_val_t)0; }
+
+el_val_t camera_capture_jpeg(el_val_t path) {
+    (void)path;
+    return (el_val_t)0;
+}
+
+#endif /* !__APPLE__ */

lang/runtime/el_runtime.h

@@ -80,6 +80,92 @@ void      println(el_val_t s);
 void      print(el_val_t s);
 el_val_t  readline(void);
 
+/* stderr counterpart of println (defined in el_seed.c). El could write to
+ * stdout and nowhere else, which is right for a program's RESULT and wrong for
+ * everything about how that result was produced. Disclosure especially has to
+ * leave on a stream the caller can separate from the answer: a program that
+ * announces "I am about to open the microphone" on stdout has corrupted its own
+ * output. Flushed on every call, so a disclosure reaches the terminal BEFORE
+ * the device it describes is touched rather than whenever the buffer drains. */
+void      eprintln(el_val_t s);
+
+/* ── Peripheral: the speaker, the microphone, the camera ─────────────────────
+ *
+ * El's I/O organ. Implemented per platform in its OWN translation unit —
+ * el_audio_darwin.m / el_capture_darwin.m on Darwin, el_peripheral_null.c
+ * everywhere else — so El code that speaks or listens links on every platform
+ * and merely reports having no device where there isn't one. Declared here and
+ * deliberately NOT implemented in el_runtime.c: acquiring a device must not
+ * mean editing the middle of the language, the same rule the realizer registry
+ * follows for modalities.
+ *
+ * These are the ONLY parts of the organ that are not El. Everything above the
+ * sample buffer — WAV encode/decode, LPC autocorrelation, Levinson-Durbin,
+ * formant extraction, source-filter resynthesis, the compact descriptors, the
+ * converse decision loop — is arithmetic, and arithmetic belongs in El. What
+ * remains here is what El cannot express: handing a buffer to the DAC and
+ * waiting for it to drain, and asking the OS for frames off a capture device.
+ *
+ * Local by construction: none of these entry points has a network path. Samples
+ * and pixels go to and from local hardware and nowhere else. Consent is
+ * enforced ABOVE this layer in El (peripheral/src/organ.el) for the Neuron-level
+ * grant, and BELOW it by the OS for TCC; capture fails closed on either.       */
+
+/* Speaker (efferent). speaker_play_pcm16 BLOCKS until the audio has actually
+ * been played rather than merely queued, so a caller can sequence utterances
+ * without guessing durations and without clipping each tail. */
+el_val_t  speaker_available(void);                 /* 1 if a real speaker backs this build */
+el_val_t  speaker_name(void);                      /* backend id, e.g. "coreaudio-audioqueue" */
+el_val_t  speaker_play_pcm16(el_val_t samples, el_val_t sample_rate);  /* [Int] 16-bit mono; 1 ok */
+el_val_t  speaker_play_wav(el_val_t path);         /* 16-bit mono RIFF/WAVE; 1 ok */
+
+/* Asynchronous playback — required by converse, which must keep listening while
+ * it speaks and must be able to stop ON THE SPOT mid-buffer. A blocking play
+ * cannot be interrupted, and "finish the current buffer" is not barge-in.
+ * speaker_stop() halts output immediately; speaker_playing() reports whether
+ * the hardware is still going; speaker_played_frames() is how far it actually
+ * got, which is what makes an interrupted utterance resumable at the sample. */
+el_val_t  speaker_play_pcm16_async(el_val_t samples, el_val_t sample_rate);
+el_val_t  speaker_play_wav_async(el_val_t path);
+el_val_t  speaker_pause(void);     /* stop AT THIS SAMPLE, keep position */
+el_val_t  speaker_resume(void);    /* carry on from exactly there */
+el_val_t  speaker_playing(void);
+el_val_t  speaker_stop(void);
+el_val_t  speaker_played_frames(void);
+
+/* WAV geometry without playing — wav-info, and the segment duration converse
+ * needs to turn elapsed time into progress. */
+el_val_t  wav_frames(el_val_t path);
+el_val_t  wav_rate(el_val_t path);
+
+/* Microphone (afferent). Fails CLOSED: returns 0 unless the OS has granted
+ * capture access. mic_capture_pcm16 blocks for `seconds` and returns an [Int]
+ * of 16-bit mono samples at `sample_rate` — the raw stream is handed to El and
+ * never written anywhere by this layer. mic_available() reports device +
+ * permission state without prompting. */
+el_val_t  mic_available(void);                     /* 1 device present AND OS-authorized */
+el_val_t  mic_request_access(void);                /* prompt once; 1 if granted */
+el_val_t  mic_capture_pcm16(el_val_t seconds, el_val_t sample_rate);   /* [Int], empty on refusal */
+
+/* Live monitoring for full-duplex converse. mic_monitor_start enables the OS
+ * voice-processing unit (acoustic echo cancellation) so the microphone does not
+ * hear the speaker — without AEC, Neuron barges in on its own voice and
+ * turn-taking is unusable in a real room. mic_monitor_rms returns the current
+ * short-window RMS as a Float in 0..1. */
+el_val_t  mic_monitor_start(void);                 /* 1 ok; 2 = started but AEC unavailable */
+el_val_t  mic_monitor_rms(void);                   /* Float */
+el_val_t  mic_monitor_stop(void);
+
+/* Camera (afferent). Fails CLOSED like the microphone. camera_capture_rgb
+ * returns a Map with width/height and the frame as an [Int] of packed RGB
+ * bytes, so the descriptor arithmetic can happen in El rather than here.
+ * camera_capture_jpeg writes an encoded frame via ImageIO, which is a codec and
+ * not something El should re-implement. */
+el_val_t  camera_available(void);
+el_val_t  camera_request_access(void);
+el_val_t  camera_capture_rgb(void);                /* Map{width,height,pixels:[Int]} or 0 */
+el_val_t  camera_capture_jpeg(el_val_t path);      /* 1 ok */
+
 /* ── String builtins ─────────────────────────────────────────────────────── */
 
 el_val_t  el_str_concat(el_val_t a, el_val_t b);

lang/runtime/el_seed.c

@@ -154,9 +154,18 @@ static void seed_request_start(void) {
  * file still links on its own. */
 __attribute__((weak)) void el_str_cache_flush(void);
 
+/* Byte-buffer capacity registry (defined below, next to the string
+ * primitives). The arena frees the pointers it tracked, so any capacity
+ * entry for those addresses must go with them — otherwise a later malloc
+ * reusing the address would inherit a stale width. */
+static void seed_cap_drop(const char* p);
+
 static void seed_request_end(void) {
     _seed_arena_on = 0;
-    for (size_t i = 0; i < _seed_arena.count; i++) free(_seed_arena.ptrs[i]);
+    for (size_t i = 0; i < _seed_arena.count; i++) {
+        seed_cap_drop(_seed_arena.ptrs[i]);
+        free(_seed_arena.ptrs[i]);
+    }
     _seed_arena.count = 0;
     if (el_str_cache_flush) el_str_cache_flush();   /* freed pointers may be reused */
 }
@@ -188,6 +197,114 @@ static char* seed_strbuf(size_t n) {
 
 static el_val_t seed_wrap_str(char* s) { return EL_STR(s); }
 
+/* ── Byte-buffer capacity registry ────────────────────────────────────────────
+ * A String produced by __str_alloc is a fixed-size BYTE BUFFER, not text. Its
+ * length is the capacity it was asked for; strlen() is meaningless on it,
+ * because the buffer is zero-filled and binary content (PCM audio, RIFF
+ * headers, image rasters) contains NUL bytes by nature.
+ *
+ * Before this registry existed, __str_set_char bounds-checked the write index
+ * against strlen(p). For a freshly __str_alloc'd buffer strlen(p) == 0, so the
+ * check `idx >= len` rejected EVERY index and the function was a total no-op:
+ * every El program that built bytes this way wrote a file of pure zeros and
+ * still saw a success return. That is why El's own-core WAV writer emitted
+ * 55,244 silent bytes with a correct-looking header length and no header.
+ *
+ * The fix cannot be "trust the index", because that removes the bound. It also
+ * cannot be a length header stored behind the pointer, because __str_set_char
+ * accepts any String — including a string literal in .rodata, where reading the
+ * bytes preceding the pointer is undefined and may fault. So capacity is kept
+ * in a side table keyed by the pointer itself: allocation registers, the arena
+ * sweep unregisters, and anything not registered keeps the exact strlen
+ * behaviour it had before. Text semantics are unchanged; byte buffers gain the
+ * bound they always should have had.                                         */
+
+typedef struct {
+    char*  ptr;   /* NULL = empty slot, (char*)1 = tombstone */
+    size_t cap;
+} SeedCapEntry;
+
+#define SEED_CAP_TOMB ((char*)1)
+
+static _Thread_local SeedCapEntry* _seed_cap      = NULL;
+static _Thread_local size_t        _seed_cap_mask = 0;   /* table size - 1 */
+static _Thread_local size_t        _seed_cap_used = 0;   /* live + tombstoned */
+
+static size_t seed_cap_hash(const char* p) {
+    uintptr_t h = (uintptr_t)p >> 4;         /* malloc alignment: low bits are dead */
+    h *= (uintptr_t)0x9E3779B97F4A7C15ull;
+    return (size_t)(h >> 32);
+}
+
+static void seed_cap_put(char* p, size_t cap);
+
+static void seed_cap_grow(void) {
+    size_t old_size = _seed_cap_mask ? _seed_cap_mask + 1 : 0;
+    SeedCapEntry* old = _seed_cap;
+    size_t new_size = old_size ? old_size * 2 : 256;
+    SeedCapEntry* fresh = calloc(new_size, sizeof(SeedCapEntry));
+    if (!fresh) return;                       /* out of memory: keep old table */
+    _seed_cap      = fresh;
+    _seed_cap_mask = new_size - 1;
+    _seed_cap_used = 0;
+    for (size_t i = 0; i < old_size; i++) {
+        if (old[i].ptr && old[i].ptr != SEED_CAP_TOMB) seed_cap_put(old[i].ptr, old[i].cap);
+    }
+    free(old);
+}
+
+static void seed_cap_put(char* p, size_t cap) {
+    if (!p) return;
+    if (!_seed_cap || (_seed_cap_used + 1) * 4 >= (_seed_cap_mask + 1) * 3) {
+        seed_cap_grow();
+        if (!_seed_cap) return;
+    }
+    size_t i = seed_cap_hash(p) & _seed_cap_mask;
+    size_t first_free = (size_t)-1;
+    for (;;) {
+        char* e = _seed_cap[i].ptr;
+        if (e == p) { _seed_cap[i].cap = cap; return; }       /* address reused */
+        if (e == SEED_CAP_TOMB && first_free == (size_t)-1) first_free = i;
+        if (!e) {
+            if (first_free != (size_t)-1) i = first_free; else _seed_cap_used++;
+            _seed_cap[i].ptr = p;
+            _seed_cap[i].cap = cap;
+            return;
+        }
+        i = (i + 1) & _seed_cap_mask;
+    }
+}
+
+/* Capacity of a registered byte buffer, or -1 when the pointer is not one. */
+static int64_t seed_cap_get(const char* p) {
+    if (!p || !_seed_cap) return -1;
+    size_t i = seed_cap_hash(p) & _seed_cap_mask;
+    for (;;) {
+        char* e = _seed_cap[i].ptr;
+        if (!e) return -1;
+        if (e == (char*)p) return (int64_t)_seed_cap[i].cap;
+        i = (i + 1) & _seed_cap_mask;
+    }
+}
+
+static void seed_cap_drop(const char* p) {
+    if (!p || !_seed_cap) return;
+    size_t i = seed_cap_hash(p) & _seed_cap_mask;
+    for (;;) {
+        char* e = _seed_cap[i].ptr;
+        if (!e) return;
+        if (e == (char*)p) { _seed_cap[i].ptr = SEED_CAP_TOMB; return; }
+        i = (i + 1) & _seed_cap_mask;
+    }
+}
+
+/* Effective addressable length of a String: its buffer capacity when it is a
+ * byte buffer, otherwise strlen. */
+static int64_t seed_addressable_len(const char* p) {
+    int64_t cap = seed_cap_get(p);
+    return cap >= 0 ? cap : (int64_t)strlen(p);
+}
+
 /* ── String primitives ───────────────────────────────────────────────────── */
 
 el_val_t __str_len(el_val_t s) {
@@ -199,7 +316,7 @@ el_val_t __str_len(el_val_t s) {
 el_val_t __str_char_at(el_val_t s, el_val_t i) {
     const char* p = EL_CSTR(s);
     if (!p) return 0;
-    int64_t len = (int64_t)strlen(p);
+    int64_t len = seed_addressable_len(p);   /* capacity for byte buffers */
     int64_t idx = (int64_t)i;
     if (idx < 0 || idx >= len) return 0;
     return (el_val_t)(unsigned char)p[idx];
@@ -210,13 +327,14 @@ el_val_t __str_alloc(el_val_t n) {
     if (sz < 0) sz = 0;
     char* buf = seed_strbuf((size_t)sz);
     memset(buf, 0, (size_t)sz + 1);
+    seed_cap_put(buf, (size_t)sz);   /* this is a byte buffer of width sz */
     return seed_wrap_str(buf);
 }
 
 el_val_t __str_set_char(el_val_t s, el_val_t i, el_val_t c) {
     char* p = (char*)(uintptr_t)s;
     if (!p) return s;
-    int64_t len = (int64_t)strlen(p);
+    int64_t len = seed_addressable_len(p);   /* capacity for byte buffers */
     int64_t idx = (int64_t)i;
     if (idx < 0 || idx >= len) return s;
     p[idx] = (char)(unsigned char)(int64_t)c;
@@ -406,6 +524,15 @@ el_val_t __fs_mkdir(el_val_t path) {
     return 1;
 }
 
+/* stderr counterpart of println. Flushed immediately: a disclosure line is only
+ * worth anything if it lands before the thing it discloses happens. */
+void eprintln(el_val_t s) {
+    const char* p = EL_CSTR(s);
+    fputs(p ? p : "", stderr);
+    fputc('\n', stderr);
+    fflush(stderr);
+}
+
 el_val_t __fs_write_bytes(el_val_t path, el_val_t bytes, el_val_t n) {
     const char* p = EL_CSTR(path);
     const char* b = EL_CSTR(bytes);

peripheral/README.md

@@ -1,80 +1,184 @@
-# peripheral — Neuron's I/O organ (own-core, local, consent-gated)
+# peripheral — Neuron's I/O organ, in El
 
-The interface made physical. Two afferent senses in, one efferent voice out —
-all reached the way the agentic surface reaches any tool.
+**El speaks.** The engram stores geometry and does not speak; the speaking
+belongs to the language and its runtime.
+
+Until this landed, the organ was a 939-line Swift program (`src/periph.swift`)
+that shelled out to `afplay`. Neuron's mouth and ears were a separate binary
+standing next to the language, and "speak" meant "ask that binary to speak."
+That program is now **reference material, not the implementation.**
 
 ```
-MIC    (hear)  afferent   device -> capture -> descriptor -> ingest -> geometry
-CAMERA (see)   afferent   device -> capture -> descriptor -> ingest -> scene-geometry
-SPEAKER(speak) efferent   render WAV -> PLAY ALOUD out the speaker
+SPEAKER (speak)  efferent   samples ──────────────► CoreAudio ──► the room
+MIC     (hear)   afferent   device ──► samples ──► descriptor ──► engram
+CAMERA  (see)    afferent   device ──► frame   ──► descriptor ──► engram
 ```
 
-Closes the conversational loop: **hear (mic) -> understand (engram) -> speak (speaker)**.
+## The split, and why it falls where it does
+
+Exactly **two** things here are not El, and they are the two things El cannot
+express as arithmetic:
+
+| Not El (realizers) | Why |
+|---|---|
+| `lang/runtime/el_audio_darwin.m` | Handing a buffer to the DAC and waiting for it to drain. There is no way to say "the hardware has now played these samples" in El, and there should not be. |
+| `lang/runtime/el_capture_darwin.m` | Asking the OS for samples off a microphone or frames off a camera, plus the TCC permission dance. |
+
+**Everything else is El**, because everything else is arithmetic:
+
+| In El | Where |
+|---|---|
+| WAV encode / decode (chunk-walking, JUNK/FLLR tolerant) | `src/organ_dsp.el`, `elp/src/speech.el` |
+| LPC autocorrelation + Levinson-Durbin (order 16 @ 16 kHz) | `src/organ_dsp.el` |
+| Formant extraction off the all-pole spectral envelope | `src/organ_dsp.el` |
+| Source-filter resynthesis (glottal impulse train through the filter) | `src/organ_dsp.el` |
+| Audio descriptor `[seconds, sr, ch, rms, peak, zcr, centroid, F0]` | `src/organ_dsp.el` |
+| Voice descriptor `[F0, F1..F5, bandwidths]` | `src/organ_dsp.el` |
+| Scene descriptor `[w, h, meanRGB, brightness, 3×3 luminance grid]` | `src/organ.el` |
+| Consent, disclosure, the voice-from-engram fetch | `src/organ.el` |
+| Barge-in, yield-or-hold, backchannel, resume | `src/organ_converse.el` |
+| The command surface | `src/organ_cli.el` |
+
+Both realizers are their **own translation units**, declared in
+`lang/runtime/el_runtime.h`, and deliberately **not** patches to
+`el_runtime.c`. Acquiring a device must not mean editing the middle of the
+language — the same rule the realizer registry follows for modalities.
+`lang/runtime/el_peripheral_null.c` provides the identical entry points
+everywhere else, so El that speaks links on any platform and truthfully reports
+having no speaker rather than going quietly silent.
+
+## The voice comes from the engram
+
+A voice is **geometry in the engram**, not a JSON file next to the code and
+certainly not constants in a source file. The organ fetches it the way anything
+retrieves a memory — it asks:
+
+```el
+let g: [Int] = organ_voice_fetch("will")
+// [peripheral] VOICE: fetched 'will' FROM THE ENGRAM —
+//              f0=137 f0_end=116 kf=1269 f1=500 f2=2093 f3=3531
+```
+
+`organ_voice_fetch` issues an engram query and reads the geometry off the node
+that comes back. Nothing opens a file. If the region is not in the graph it
+returns **empty**, not a plausible default — a caller has to be able to tell
+"this is how they sound" from "I never heard them."
+
+The reverse direction is `ingest-voice`: an LPC voiceprint becomes a node, and
+from then on the voice is a memory rather than a measurement someone wrote down.
+
+## What the organ never does
+
+**It never learns a word.** Pronunciation, vocabulary and phonemes belong to the
+language faculty and are already built as ingested geometry — *the engram knows
+how to pronounce*. The seam is `synth_codes(codes, voice, pmap)`: the codes and
+the phoneme map arrive from the language side as geometry, and the organ's whole
+job is turning them into samples and getting the samples out the speaker, plus
+the same trip in reverse for the senses. There is no lexicon here and no
+grapheme-to-phoneme rule, by design.
 
 ## Rails
-- **Own-core.** macOS-native only: AVFoundation (camera/mic), CoreAudio voice-
-  processing (AEC), afplay (speaker), ImageIO/CoreGraphics (frames), hand-rolled
-  DSP (WAV, LPC, formant synthesis). No cloud, no heavy deps.
-- **Local-only.** Raw streams are written to `out/` and never egress. `.gitignore`
-  keeps captured media out of git.
-- **Consent-gated (two locks).** A Neuron-level grant (`grant`/`revoke`) *and* the
-  OS TCC permission. Sensitive senses (camera/mic) fail closed without both.
-- **Disclosed.** Every device touch prints a `[peripheral]` line on stderr.
+
+- **Own-core.** CoreAudio / AVFoundation / ImageIO — all ship with macOS. No
+  cloud, no model, no heavy dependency. There is **no network code in the organ
+  at all**, by construction.
+- **Local-only.** Raw streams stay on the machine. What leaves a capture is a
+  descriptor of a few dozen numbers. A 1920×1080 frame becomes 15 integers
+  (~414,000× smaller); three seconds of audio becomes 8.
+- **Consent, two locks.** A Neuron-level grant **and** the OS TCC permission.
+  Camera and mic **fail closed** without both. The speaker is disclosed but not
+  gated — you cannot secretly speak aloud, and gating it would mean Neuron needs
+  permission to answer.
+- **Disclosed.** Every device touch prints a `[peripheral]` line on **stderr**
+  (via `eprintln`, flushed immediately), so a disclosure lands before the device
+  is touched and never contaminates the program's stdout.
 
 ## Build
+
+```bash
+./peripheral/build.sh /tmp/organ
 ```
-swiftc -O -o bin/periph src/periph.swift \
-  -framework AVFoundation -framework CoreMedia -framework Foundation \
-  -framework CoreGraphics -framework ImageIO -framework CoreImage
-```
+
+Concatenates the El modules, compiles with `elc`, links the two realizers.
+Run it **from the repo root** or the `.psv` phoneme data will not resolve.
 
 ## Commands
+
 ```
-periph grant|revoke <camera|mic>          # Neuron-level consent
-periph status
-periph speak <file.wav>                   # SPEAK ALOUD (efferent)
-periph tone <out.wav> [hz] [sec]          # own-core WAV synth
-periph listen <sec> <out.wav>             # MIC capture (afferent), 16k mono
-periph see <out.jpg>                      # CAMERA one frame (afferent)
-periph feat-audio <wav> | feat-image <jpg>          # capture -> compact descriptor
-periph ingest-audio|ingest-image <file> <engramURL> # descriptor -> engram node (geometry)
-periph voiceprint <voice.wav>             # extract F0 + formants F1-F5
-periph imitate <voice.wav> <out.wav>      # speak back in that voice (LPC resynthesis)
-periph hear-imitate <sec> <out.wav>       # MIC -> signature -> imitate -> SPEAK ALOUD
-periph converse <manifest.json> [--authority F] [--barge-at S[:backchannel|:bargein]] [--resume] [--live-mic]
+organ grant|revoke <camera|mic>     Neuron-level consent
+organ status                        consent + device state
+organ speak <file.wav>              play a WAV aloud (efferent)
+organ tone [hz] [ms]                synthesize and play — no file at all
+organ say <voice> <CODE> [CODE...]  fetch voice FROM THE ENGRAM, render, speak
+organ listen <sec> <out.wav>        mic capture 16k mono (afferent)
+organ see <out.jpg>                 one camera frame (afferent)
+organ wav-info <file.wav>           WAV geometry
+organ feat-audio <file.wav>         compact audio descriptor (8 numbers)
+organ feat-image                    compact scene-geometry from the camera
+organ voiceprint <voice.wav>        F0 + formants F1-F5 (LPC)
+organ imitate <in.wav> <out.wav>    LPC analysis-resynthesis
+organ hear-imitate <sec> <out.wav>  mic -> signature -> imitate -> speak aloud
+organ ingest-audio <file.wav>       descriptor -> engram node (geometry)
+organ ingest-voice <voice.wav> <n>  voiceprint -> engram voice region
+organ converse <manifest.json> [--authority PM] [--barge-at MS[:kind]] [--live-mic] [--resume]
 ```
 
-## The afferent metabolism
-A capture is never shipped raw. It becomes a **compact descriptor** — the afferent
-twin of the music instrument-signature:
-- audio -> `[seconds, sr, ch, rms, peak, zcr, centroid, F0]` (~2400-6000x smaller)
-- image -> `[w, h, meanRGB, brightness, 3x3 luminance grid]` (~400000x smaller)
-- voice -> `[F0, F1..F5, bandwidths]` (11 numbers)
+## Interruptibility
 
-That descriptor is what the ingest organ (engram `POST /api/nodes`) turns into an
-embedded node = geometry.
+`converse` speaks an ordered, salience-tagged **meaning-plan** while listening:
 
-## Voice by imitation
-`voiceprint`/`imitate` are own-core LPC (autocorrelation + Levinson-Durbin, order
-16 @ 16 kHz), formant extraction from the LPC spectral envelope, and source-filter
-resynthesis (glottal impulse train at F0 through the all-pole formant filter). A
-voice is grabbed by ear as ~a dozen numbers and spoken back — **no training, no
-stolen voice.** Measured fidelity on real speech: resynthesized formants match the
-source within 2-3%. The full phoneme->formant path for *novel* sentences is the
-speech faculty's seam (`elp` audio surface profile); this engine provides the
-formant synthesis primitive it renders through.
+- **barge-in** — output stops at the sample, not at the end of the buffer. The
+  realizer exposes `pause`/`resume` and reports `played_frames` (the real DAC
+  position) precisely so this is possible.
+- **yield-or-hold** — a decision, not a rule: `hold = salience·0.6 +
+  progress·0.4`, and holding also requires that the interrupter not be
+  high-authority. Otherwise yield, because the polite default is the right one.
+- **backchannel** — "mm-hm" is brief and low-energy; resume seamlessly.
+- **resumable** — on yield the remaining plan persists to `.resume.json`;
+  `--resume` picks the thread back up. An interruption should cost a turn, not
+  the content.
 
-## Interruptibility (native turn-taking)
-`converse` plays the utterance as an ordered, salience-tagged **meaning-plan**
-while the mic listens (full-duplex, AEC on so it never barges in on its own voice):
-- **barge-in**: user speech -> pause on the spot (sample-accurate), not "finish the buffer."
-- **yield-or-hold**: a decision grounded in the current segment's salience + progress
-  + the interrupter's authority — YIELD (stop) or HOLD ("hang on, let me finish").
-- **backchannel** ("mm-hm"): brief/low -> keep going, resume seamlessly.
-- **resumable**: on yield the remaining plan persists (`.resume.json`); `--resume`
-  picks the thread back up ("as I was saying").
+Live full-duplex uses `--live-mic` with the OS voice-processing unit (AEC) so
+Neuron does not barge in on its own voice. `--barge-at` injects the event
+deterministically for testing.
 
-Live full-duplex uses `--live-mic` (OS AEC). Injected `--barge-at` drives the
-decision loop deterministically for testing.
-```
-```
+## Measured against the Swift original
+
+Same input (`out/mic_room.wav`, 16 kHz mono, 48121 samples), Swift `periph`
+vs the El organ:
+
+| | Swift | El |
+|---|---|---|
+| seconds | 3.0075625 | 3.0076 |
+| rms | 0.0047766496761 | 0.004777 |
+| peak | 0.01806640625 | 0.018066 |
+| zcr_hz | 416.28395087 | 416.2840 |
+| centroid_hz | 727.60529169 | 727.6053 |
+| f0_hz | 400 | 400.0000 |
+| formants F1–F5 | 1734.375 / 3343.75 / 3875 / 4359.375 / 4468.75 | identical |
+| bandwidths B1–B5 | 2000 / 2968.75 / 4203.125 / 4687.5 / 5000 | identical |
+
+Agreement to every printed digit. `imitate` cannot match bit-for-bit because the
+Swift excites unvoiced frames with `Double.random` — two Swift runs correlate
+0.957 with **each other**; El correlates **0.958** with Swift. The port is as
+close to the original as the original is to itself, and the deterministic prefix
+is bit-identical.
+
+## Honest status
+
+- **Works:** speaker (CoreAudio, no `afplay`, no subprocess — verified: zero
+  `afplay`/Swift strings in the binary, no child process during playback), mic
+  capture, camera capture, all descriptors, LPC voiceprint, imitate,
+  hear-imitate, voice fetch/ingest against the engram, converse (yield, hold,
+  yield-to-authority, backchannel, resume — all exercised with real audio).
+- **Coarse, and labelled so:** a fetched voice is one formant triple with no
+  coarticulation and no prosody. It is an impression, explicitly **not a
+  clone**, and `prov=COARSE` says so on the node.
+- **Not verified here:** live `--live-mic` barge-in in a real room with a real
+  interrupter. The AEC path is implemented and the deterministic path is proven;
+  the acoustic behaviour is not something a headless run can establish.
+- **Not in the engram yet:** the structured `Voice` / `VowelTarget` geometry
+  nodes live in the organ's own store and in snapshot files from earlier work,
+  but the **production engram does not carry them**. Getting them there is an
+  ingest, not a code change.
+- `src/periph.swift` is kept as the reference the port was measured against.

peripheral/build.sh

@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+# build.sh — build the El organ.
+#
+# El has no import system on this path, so the modules are concatenated in
+# dependency order (the same thing elp/tests/run.sh does) and handed to elc as
+# one unit. The two device realizers are then linked in.
+#
+# MUST be run from the repo root, or the .psv phoneme geometry will not resolve
+# and the render silently degrades.
+set -uo pipefail
+
+OUT="${1:-./peripheral/organ}"
+REPO="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$REPO"
+
+WORK="$(mktemp -d)"
+trap 'rm -rf "$WORK"' EXIT
+
+# Dependency order. The elp modules supply the render (synth_codes) and the
+# phoneme-geometry read; the organ supplies everything else.
+cat elp/src/voice-profile.el \
+    elp/src/accent.el \
+    elp/src/voice-ingest.el \
+    elp/src/speech-ingest.el \
+    elp/src/speech.el \
+    peripheral/src/organ.el \
+    peripheral/src/organ_dsp.el \
+    peripheral/src/organ_converse.el \
+    peripheral/src/organ_cli.el \
+  | grep -v '^import ' > "$WORK/organ.el"
+
+cd "$REPO/lang"
+./dist/platform/elc "$WORK/organ.el" > "$WORK/organ.c" || { echo "elc failed" >&2; exit 1; }
+
+SSL_PREFIX="$(brew --prefix openssl@3 2>/dev/null || echo /usr/local)"
+
+# The peripheral realizers are per-platform: Darwin gets the real devices,
+# anything else gets el_peripheral_null.c and honestly reports having none.
+case "$(uname)" in
+  Darwin)
+    # The Objective-C realizers are compiled SEPARATELY, with -fobjc-arc. The
+    # capture realizer is written against ARC (it holds AVFoundation objects);
+    # compiling it MRR silently changes its memory semantics, which on a device
+    # path shows up as a use-after-free under load rather than as an error here.
+    cc -std=c11 -fobjc-arc -O1 -I runtime -c runtime/el_audio_darwin.m   -o "$WORK/el_audio.o"   || exit 1
+    cc -std=c11 -fobjc-arc -O1 -I runtime -c runtime/el_capture_darwin.m -o "$WORK/el_capture.o" || exit 1
+    PERIPH_SRC="$WORK/el_audio.o $WORK/el_capture.o"
+    PERIPH_LIBS="-framework AudioToolbox -framework AVFoundation -framework CoreMedia
+                 -framework CoreVideo -framework CoreGraphics -framework ImageIO
+                 -framework Foundation"
+    ;;
+  *)
+    PERIPH_SRC="runtime/el_peripheral_null.c"
+    PERIPH_LIBS=""
+    ;;
+esac
+
+cc -O1 -I runtime -I"$SSL_PREFIX/include" -L"$SSL_PREFIX/lib" \
+   -o "$OUT" "$WORK/organ.c" \
+   runtime/el_runtime.c runtime/el_seed.c \
+   runtime/engram_cognition.c runtime/engram_geometry.c runtime/engram_reason.c \
+   runtime/engram_store.c runtime/engram_verify.c runtime/engram_vindex.c \
+   runtime/eg_cosine_batch.c runtime/eg_cosine_batch_strategy_cpu.c \
+   $PERIPH_SRC $PERIPH_LIBS \
+   -lcurl -lssl -lcrypto -lpthread -lm || { echo "link failed" >&2; exit 1; }
+
+echo "built: $OUT"

peripheral/src/organ.el

@@ -0,0 +1,570 @@
+// organ.el — Neuron's I/O organ, in El.
+//
+// THE PRINCIPLE. El speaks. The engram stores geometry and does not speak.
+// Before this file the organ was a 939-line Swift program standing next to the
+// language (peripheral/src/periph.swift): Neuron's mouth and ears were a
+// separate binary, and "speak" meant "shell out to that binary, which shells
+// out to afplay." That is not a voice, it is a subprocess. The voice belongs to
+// the language and its runtime.
+//
+// THE SPLIT. Exactly two things here are not El, and they are the two things El
+// cannot express as arithmetic:
+//
+//   the speaker  — handing a buffer to the DAC and waiting for it to drain
+//   the capture  — asking the OS for samples off a mic or frames off a camera
+//
+// Those live in lang/runtime/el_audio_darwin.m and el_capture_darwin.m, as
+// their own translation units, declared in el_runtime.h. Everything ELSE that
+// the Swift did — WAV encode and decode, LPC autocorrelation, Levinson-Durbin,
+// formant extraction off the all-pole envelope, source-filter resynthesis, the
+// compact descriptors, the converse yield-or-hold decision — is arithmetic, and
+// arithmetic is El's. See organ_dsp.el for that half.
+//
+// WHERE THE VOICE COMES FROM. Not from this file, and not from a JSON manifest
+// on disk. A voice is GEOMETRY IN THE ENGRAM, and the organ goes and gets it by
+// asking the engram, the same way anything else asks the engram for anything:
+// a query against the graph, then read the numbers off the node that comes
+// back. organ_voice_fetch is that. The previous path, load_voice("...json"),
+// parsed a file — which quietly made the voice a build artifact instead of a
+// memory. If the region is not in the graph, the honest answer is an empty
+// result, not a default voice.
+//
+// WHAT THE ORGAN NEVER DOES. It never learns a word. Pronunciation, vocabulary
+// and phonemes are the language faculty's, already built as ingested geometry —
+// "the engram knows how to pronounce." The seam is synth_codes(codes, voice,
+// pmap): the codes and the phoneme map arrive from the language side as
+// geometry, and the organ's whole job is turning them into samples and getting
+// the samples out the speaker, plus the same trip in reverse for the senses.
+//
+// RAILS, all non-negotiable:
+//   own-core     — CoreAudio / AVFoundation / ImageIO, all shipped with the OS.
+//                  No cloud, no model, no heavy dependency. There is no network
+//                  call anywhere in the organ, by construction.
+//   local-only   — raw streams stay on the machine. What leaves a capture is a
+//                  DESCRIPTOR of a few dozen numbers, never the stream.
+//   consent      — two locks on the sensitive senses: a Neuron-level grant AND
+//                  the OS TCC permission. Camera and mic FAIL CLOSED without
+//                  both. The speaker is disclosed but not gated (see below).
+//   disclosed    — every device touch prints a [peripheral] line on stderr.
+//                  Nothing here is ever silent about being a device.
+
+// ── Disclosure ───────────────────────────────────────────────────────────────
+//
+// stderr, not stdout: a program that announces "I am opening the microphone" on
+// stdout has corrupted its own output. And flushed immediately, so the line is
+// on the terminal BEFORE the device is touched — a disclosure that arrives
+// after the fact is a log, not a disclosure.
+
+fn organ_disclose(msg: String) -> Bool {
+    eprintln("  [peripheral] " + msg)
+    return true
+}
+
+// ── Consent, the Neuron-level lock ───────────────────────────────────────────
+//
+// The OS has its own lock (TCC) and it is not enough on its own: TCC grants the
+// TERMINAL access to the microphone, once, more or less forever. That says the
+// user trusts the app. It does not say the user consents to THIS program
+// listening THIS time. So Neuron keeps its own grant, revocable, on the same
+// footing — and both must be open for a sensitive sense to work.
+//
+// Stored next to the organ rather than in the engram deliberately: consent must
+// be inspectable and revocable without a running graph, and a permission that
+// can only be revoked by the system it governs is not a permission.
+
+fn organ_consent_path() -> String {
+    let home: String = env("PERIPH_HOME")
+    if str_eq(home, "") {
+        return "peripheral/.consent.json"
+    }
+    return home + "/.consent.json"
+}
+
+fn organ_consent_granted(device: String) -> Bool {
+    let raw: String = fs_read(organ_consent_path())
+    if str_eq(raw, "") {
+        return false
+    }
+    // A device is granted only on an explicit true. Anything unparseable,
+    // missing or malformed reads as NOT granted — the failure direction for a
+    // permission file is always closed.
+    let key: String = "\"" + device + "\""
+    let at: Int = str_index_of(raw, key)
+    if at < 0 {
+        return false
+    }
+    let tail: String = str_slice(raw, at, str_len(raw))
+    let t: Int = str_index_of(tail, "true")
+    let f: Int = str_index_of(tail, "false")
+    if t < 0 {
+        return false
+    }
+    if f < 0 {
+        return true
+    }
+    // whichever token appears first after the key is this device's value
+    if t < f {
+        return true
+    }
+    return false
+}
+
+fn organ_consent_write(camera: Bool, mic: Bool) -> Bool {
+    let c: String = "false"
+    if camera {
+        c = "true"
+    }
+    let m: String = "false"
+    if mic {
+        m = "true"
+    }
+    return fs_write(organ_consent_path(), "{\"camera\": " + c + ", \"mic\": " + m + "}\n")
+}
+
+fn organ_grant(device: String) -> Bool {
+    let cam: Bool = organ_consent_granted("camera")
+    let mic: Bool = organ_consent_granted("mic")
+    if str_eq(device, "camera") {
+        cam = true
+    }
+    if str_eq(device, "mic") {
+        mic = true
+    }
+    let ok: Bool = organ_consent_write(cam, mic)
+    organ_disclose("granted '" + device + "' (Neuron-level) — raw stream stays local, never egresses.")
+    return ok
+}
+
+fn organ_revoke(device: String) -> Bool {
+    let cam: Bool = organ_consent_granted("camera")
+    let mic: Bool = organ_consent_granted("mic")
+    if str_eq(device, "camera") {
+        cam = false
+    }
+    if str_eq(device, "mic") {
+        mic = false
+    }
+    let ok: Bool = organ_consent_write(cam, mic)
+    organ_disclose("revoked '" + device + "' (Neuron-level).")
+    return ok
+}
+
+fn organ_consent_status() -> String {
+    let cam: String = "denied"
+    if organ_consent_granted("camera") {
+        cam = "granted"
+    }
+    let mic: String = "denied"
+    if organ_consent_granted("mic") {
+        mic = "granted"
+    }
+    return "camera=" + cam + " mic=" + mic
+}
+
+// Both locks, in order, with a disclosure for each outcome. Returns false and
+// says exactly which lock is shut — a refusal that does not say why is
+// indistinguishable from a bug.
+fn organ_may_listen() -> Bool {
+    if organ_consent_granted("mic") == false {
+        organ_disclose("CONSENT DENIED for 'mic' (Neuron-level). Run: organ grant mic")
+        return false
+    }
+    if mic_available() == 0 {
+        organ_disclose("CONSENT DENIED for 'mic' (OS/TCC), or no input device. Grant microphone access to this terminal in System Settings > Privacy.")
+        return false
+    }
+    organ_disclose("consent OK (Neuron + OS) for 'mic' — local only, never egresses.")
+    return true
+}
+
+fn organ_may_see() -> Bool {
+    if organ_consent_granted("camera") == false {
+        organ_disclose("CONSENT DENIED for 'camera' (Neuron-level). Run: organ grant camera")
+        return false
+    }
+    if camera_available() == 0 {
+        organ_disclose("CONSENT DENIED for 'camera' (OS/TCC), or no capture device. Grant camera access to this terminal in System Settings > Privacy.")
+        return false
+    }
+    organ_disclose("consent OK (Neuron + OS) for 'camera' — local only, never egresses.")
+    return true
+}
+
+// ── SPEAKER (efferent) ───────────────────────────────────────────────────────
+//
+// Not consent-gated, and that is a deliberate asymmetry rather than an
+// oversight. The microphone and camera take information OFF the user without
+// them necessarily knowing; the speaker puts information INTO a room the user
+// is in, audibly, which is self-disclosing by its nature — you cannot secretly
+// speak aloud. So the speaker is DISCLOSED (every utterance announces itself on
+// stderr) but not gated. Gating it would mean Neuron needs permission to answer.
+
+fn organ_speak_samples(samples: [Int], sr: Int) -> Bool {
+    let n: Int = native_list_len(samples)
+    if n <= 0 {
+        organ_disclose("SPEAKER: nothing to say (0 samples) — not touching the device.")
+        return false
+    }
+    if speaker_available() == 0 {
+        organ_disclose("SPEAKER: no audio output on this build (" + speaker_name() + ") — cannot speak.")
+        return false
+    }
+    let secs: Int = n * 1000 / sr
+    organ_disclose("SPEAKER: playing " + int_to_str(n) + " samples (" + int_to_str(secs) + " ms @ " + int_to_str(sr) + " Hz) ALOUD via " + speaker_name() + " (efferent).")
+    let ok: Int = speaker_play_pcm16(samples, sr)
+    if ok == 1 {
+        organ_disclose("SPEAKER: done — Neuron spoke aloud.")
+        return true
+    }
+    organ_disclose("SPEAKER: playback FAILED.")
+    return false
+}
+
+fn organ_speak_wav(path: String) -> Bool {
+    if speaker_available() == 0 {
+        organ_disclose("SPEAKER: no audio output on this build — cannot speak.")
+        return false
+    }
+    if fs_exists(path) == false {
+        organ_disclose("SPEAKER: no such file: " + path)
+        return false
+    }
+    organ_disclose("SPEAKER: playing '" + path + "' ALOUD via " + speaker_name() + " (efferent).")
+    let ok: Int = speaker_play_wav(path)
+    if ok == 1 {
+        organ_disclose("SPEAKER: done — Neuron spoke aloud.")
+        return true
+    }
+    organ_disclose("SPEAKER: playback FAILED.")
+    return false
+}
+
+// ── The voice, fetched FROM THE ENGRAM ───────────────────────────────────────
+//
+// This is the part that matters most and is easiest to get subtly wrong. A
+// voice is not a constant in code and it is not a JSON file next to the code —
+// it is a region of the graph, put there by having heard someone, and the organ
+// retrieves it the way anything retrieves a memory: by asking.
+//
+// The node content is the geometry, in the engram's own flat key=value form:
+//   voice will | f0=137 f0_end=116 kf=1269 f1=500 f2=2093 f3=3531 ...
+// so the read is: query the graph, take the returned node, pull the numbers off
+// it. Nothing here opens a file.
+//
+// Returns [f0, f0_end, kf, f1, f2, f3], or an EMPTY list when the region is not
+// in the graph. Empty is the honest answer — a caller that gets no voice must
+// not be handed a plausible default and left unable to tell the difference
+// between "this is how they sound" and "I never heard them."
+
+// Read an unsigned integer that follows `key` in `s`. Stops at the first
+// non-digit, returns 0 when the key is absent.
+fn organ_int_after(s: String, key: String) -> Int {
+    let at: Int = str_index_of(s, key)
+    if at < 0 {
+        return 0
+    }
+    let i: Int = at + str_len(key)
+    let n: Int = str_len(s)
+    let v: Int = 0
+    let seen: Int = 0
+    while i < n {
+        let c: Int = str_char_code(s, i)
+        if c < 48 {
+            i = n
+        } else {
+            if c > 57 {
+                i = n
+            } else {
+                v = v * 10 + (c - 48)
+                seen = seen + 1
+                i = i + 1
+            }
+        }
+    }
+    if seen == 0 {
+        return 0
+    }
+    return v
+}
+
+// Ask the engram for a named voice region and read its geometry back.
+fn organ_voice_fetch(name: String) -> [Int] {
+    let out: [Int] = native_list_empty()
+    let marker: String = "voice " + name + " |"
+    // The graph is asked by MEANING, not by id or by path.
+    let hits: String = engram_search_json("voice " + name + " f0 formants", 12)
+    let at: Int = str_index_of(hits, marker)
+    if at < 0 {
+        // Fall back to a scan of the resident graph before giving up: search is
+        // geometric and a small graph may not rank the region first.
+        let scan: String = engram_scan_nodes_json(500, 0)
+        at = str_index_of(scan, marker)
+        if at < 0 {
+            organ_disclose("VOICE: no region for '" + name + "' in the engram — nothing to speak with.")
+            return out
+        }
+        hits = scan
+    }
+    let win: String = str_slice(hits, at, at + 240)
+    out = native_list_append(out, organ_int_after(win, "f0="))
+    out = native_list_append(out, organ_int_after(win, "f0_end="))
+    out = native_list_append(out, organ_int_after(win, "kf="))
+    out = native_list_append(out, organ_int_after(win, "f1="))
+    out = native_list_append(out, organ_int_after(win, "f2="))
+    out = native_list_append(out, organ_int_after(win, "f3="))
+    organ_disclose("VOICE: fetched '" + name + "' FROM THE ENGRAM — f0=" + int_to_str(native_list_get(out, 0)) + " f0_end=" + int_to_str(native_list_get(out, 1)) + " kf=" + int_to_str(native_list_get(out, 2)) + " f1=" + int_to_str(native_list_get(out, 3)) + " f2=" + int_to_str(native_list_get(out, 4)) + " f3=" + int_to_str(native_list_get(out, 5)))
+    return out
+}
+
+// Put a measured voice INTO the engram as geometry. This is the afferent end of
+// the same wire: a voiceprint (organ_dsp.el's LPC analysis) becomes a node, and
+// from then on the voice is a memory rather than a measurement someone happened
+// to write down. `prov` carries the honesty: COARSE means one formant triple, no
+// coarticulation, no prosody — an impression, explicitly not a clone.
+fn organ_voice_ingest(name: String, f0: Int, f0_end: Int, kf: Int, f1: Int, f2: Int, f3: Int, src: String, prov: String) -> String {
+    let hub: String = engram_node("voice-signature-set " + name + " grounding=measured src=" + src, "VoiceSet", 90)
+    let body: String = "voice " + name + " | f0=" + int_to_str(f0) + " f0_end=" + int_to_str(f0_end) + " kf=" + int_to_str(kf) + " f1=" + int_to_str(f1) + " f2=" + int_to_str(f2) + " f3=" + int_to_str(f3) + " grounding=measured src=" + src + " prov=" + prov
+    let vid: String = engram_node(body, "Voice", 90)
+    engram_connect(hub, vid, 90, "has-signature")
+    organ_disclose("VOICE: ingested '" + name + "' into the engram as geometry (node " + vid + ").")
+    return vid
+}
+
+// Turn the fetched geometry into the voice slot-map the render consumes. Kept
+// separate from the fetch so the organ never invents a voice: if the fetch came
+// back empty this returns empty too, and the caller has to deal with it.
+//
+// The slot-map is built here rather than by calling the render's own
+// constructor, so the organ carries NO dependency on the language faculty's
+// modules — it only has to agree with them about a wire format, which is the
+// looser and more honest coupling. (The layout is the same key/value [String]
+// convention lang_get / surface_get / voice_get all read.)
+fn organ_voice_profile(name: String, g: [Int]) -> [String] {
+    let r: [String] = native_list_empty()
+    if native_list_len(g) < 6 {
+        return r
+    }
+    r = native_list_append(r, "name")
+    r = native_list_append(r, name)
+    r = native_list_append(r, "f0")
+    r = native_list_append(r, int_to_str(native_list_get(g, 0)))
+    r = native_list_append(r, "f0_end")
+    r = native_list_append(r, int_to_str(native_list_get(g, 1)))
+    r = native_list_append(r, "kf")
+    r = native_list_append(r, int_to_str(native_list_get(g, 2)))
+    r = native_list_append(r, "dur")
+    r = native_list_append(r, "1000")
+    r = native_list_append(r, "tilt")
+    r = native_list_append(r, "1000")
+    r = native_list_append(r, "breath")
+    r = native_list_append(r, "8")
+    return r
+}
+
+// ── Scene geometry (afferent, camera) ────────────────────────────────────────
+//
+// The image half of the afferent metabolism, and the same principle as the
+// audio descriptor: a frame is never handed on raw. The realizer returns a
+// small pixel grid; THIS computes the descriptor, in El, because averaging
+// pixels is arithmetic and arithmetic is not a device concern.
+//
+// Returns 15 numbers — [w, h, meanR, meanG, meanB, brightness_pm, and a 3x3
+// luminance grid] — standing in for a multi-megapixel frame. The 3x3 grid is
+// the smallest thing that still says WHERE the light is, which is most of what
+// makes a scene comparable to another scene; a single brightness average would
+// make a lamp on the left indistinguishable from a lamp on the right.
+//
+// Luminance is Rec. 601 (0.299R + 0.587G + 0.114B), in integer per-mille, so
+// the descriptor is reproducible rather than subject to float drift.
+fn organ_image_descriptor() -> [Int] {
+    let out: [Int] = native_list_empty()
+    let frame: Any = camera_capture_rgb()
+    if frame == 0 {
+        return out
+    }
+    let w: Int = el_map_get(frame, "width")
+    let h: Int = el_map_get(frame, "height")
+    let gw: Int = el_map_get(frame, "grid_w")
+    let gh: Int = el_map_get(frame, "grid_h")
+    let px: [Int] = el_map_get(frame, "pixels")
+    let np: Int = native_list_len(px)
+    if np < 3 {
+        return out
+    }
+    let count: Int = np / 3
+    let rsum: Int = 0
+    let gsum: Int = 0
+    let bsum: Int = 0
+    // 3x3 accumulators, row-major
+    let cell: [Int] = native_list_empty()
+    let cn: [Int] = native_list_empty()
+    let z: Int = 0
+    while z < 9 {
+        cell = native_list_append(cell, 0)
+        cn = native_list_append(cn, 0)
+        z = z + 1
+    }
+    // El has no list-set, so the cells are summed into parallel scalars and
+    // reassembled — nine explicit accumulators would be worse to read than one
+    // pass per cell over a grid this small.
+    let c0: Int = 0
+    let c1: Int = 0
+    let c2: Int = 0
+    let c3: Int = 0
+    let c4: Int = 0
+    let c5: Int = 0
+    let c6: Int = 0
+    let c7: Int = 0
+    let c8: Int = 0
+    let n0: Int = 0
+    let n1: Int = 0
+    let n2: Int = 0
+    let n3: Int = 0
+    let n4: Int = 0
+    let n5: Int = 0
+    let n6: Int = 0
+    let n7: Int = 0
+    let n8: Int = 0
+    let i: Int = 0
+    while i < count {
+        let r: Int = native_list_get(px, i * 3)
+        let g: Int = native_list_get(px, i * 3 + 1)
+        let b: Int = native_list_get(px, i * 3 + 2)
+        rsum = rsum + r
+        gsum = gsum + g
+        bsum = bsum + b
+        let lum: Int = (299 * r + 587 * g + 114 * b) / 1000
+        let x: Int = i - (i / gw) * gw
+        let y: Int = i / gw
+        let cx: Int = x * 3 / gw
+        let cy: Int = y * 3 / gh
+        if cx > 2 {
+            cx = 2
+        }
+        if cy > 2 {
+            cy = 2
+        }
+        let idx: Int = cy * 3 + cx
+        if idx == 0 {
+            c0 = c0 + lum
+            n0 = n0 + 1
+        }
+        if idx == 1 {
+            c1 = c1 + lum
+            n1 = n1 + 1
+        }
+        if idx == 2 {
+            c2 = c2 + lum
+            n2 = n2 + 1
+        }
+        if idx == 3 {
+            c3 = c3 + lum
+            n3 = n3 + 1
+        }
+        if idx == 4 {
+            c4 = c4 + lum
+            n4 = n4 + 1
+        }
+        if idx == 5 {
+            c5 = c5 + lum
+            n5 = n5 + 1
+        }
+        if idx == 6 {
+            c6 = c6 + lum
+            n6 = n6 + 1
+        }
+        if idx == 7 {
+            c7 = c7 + lum
+            n7 = n7 + 1
+        }
+        if idx == 8 {
+            c8 = c8 + lum
+            n8 = n8 + 1
+        }
+        i = i + 1
+    }
+    let rA: Int = rsum / count
+    let gA: Int = gsum / count
+    let bA: Int = bsum / count
+    let bright: Int = (299 * rA + 587 * gA + 114 * bA) / 255
+    out = native_list_append(out, w)
+    out = native_list_append(out, h)
+    out = native_list_append(out, rA)
+    out = native_list_append(out, gA)
+    out = native_list_append(out, bA)
+    out = native_list_append(out, bright)
+    if n0 < 1 {
+        n0 = 1
+    }
+    if n1 < 1 {
+        n1 = 1
+    }
+    if n2 < 1 {
+        n2 = 1
+    }
+    if n3 < 1 {
+        n3 = 1
+    }
+    if n4 < 1 {
+        n4 = 1
+    }
+    if n5 < 1 {
+        n5 = 1
+    }
+    if n6 < 1 {
+        n6 = 1
+    }
+    if n7 < 1 {
+        n7 = 1
+    }
+    if n8 < 1 {
+        n8 = 1
+    }
+    out = native_list_append(out, c0 / n0)
+    out = native_list_append(out, c1 / n1)
+    out = native_list_append(out, c2 / n2)
+    out = native_list_append(out, c3 / n3)
+    out = native_list_append(out, c4 / n4)
+    out = native_list_append(out, c5 / n5)
+    out = native_list_append(out, c6 / n6)
+    out = native_list_append(out, c7 / n7)
+    out = native_list_append(out, c8 / n8)
+    organ_disclose("FEAT(image): 15-number scene-geometry vs " + int_to_str(w * h * 3) + " pixel-channels — the descriptor travels, the frame does not.")
+    return out
+}
+
+// ── Own-core tone ────────────────────────────────────────────────────────────
+//
+// The smallest possible proof that the organ owns its medium end to end: a sine
+// with a gentle attack and release, computed here, played by us, no file and no
+// library anywhere in the path.
+fn organ_tone(hz: Int, ms: Int, sr: Int) -> [Int] {
+    let n: Int = sr * ms / 1000
+    let out: [Int] = native_list_empty()
+    let two_pi: Float = 6.283185307
+    let srf: Float = int_to_float(sr)
+    let hzf: Float = int_to_float(hz)
+    let i: Int = 0
+    // 20 ms of ramp at each end; a square-edged tone clicks, and a click is the
+    // organ announcing that it does not understand envelopes.
+    let ramp: Int = sr / 50
+    if ramp < 1 {
+        ramp = 1
+    }
+    while i < n {
+        let t: Float = int_to_float(i) / srf
+        let s: Float = math_sin(two_pi * hzf * t)
+        let env: Int = 32767
+        if i < ramp {
+            env = 32767 * i / ramp
+        }
+        let tail: Int = n - i
+        if tail < ramp {
+            env = 32767 * tail / ramp
+        }
+        let v: Int = float_to_int(s * 9000.0) * env / 32767
+        out = native_list_append(out, v)
+        i = i + 1
+    }
+    return out
+}

peripheral/src/organ_cli.el

@@ -0,0 +1,459 @@
+// organ_cli.el — the organ's command surface. main() lives here.
+//
+// One binary, the same verbs the Swift program had, and nothing behind them
+// except El and two thin device realizers. This file is the proof surface: if
+// `organ speak` makes a sound and no Swift binary is in the process tree, the
+// claim in organ.el's header is true.
+//
+// Verbs, and what each one demonstrates:
+//
+//   grant/revoke/status    the Neuron-level consent lock, inspectable
+//   speak <wav>            efferent — audio out of El's own speaker
+//   tone <hz> <ms>         own-core synthesis: computed in El, played by El,
+//                          never touching the disk
+//   say <name> <codes...>  fetch a VOICE FROM THE ENGRAM and render through it
+//   listen <sec> <out>     afferent — mic capture, consent-gated, fails closed
+//   see <out.jpg>          afferent — one camera frame, same two locks
+//   wav-info <wav>         WAV geometry, parsed in El
+//   feat-audio <wav>       capture -> compact descriptor (8 numbers)
+//   feat-image <jpg>       frame  -> compact scene-geometry
+//   voiceprint <wav>       F0 + formants F1-F5 by LPC, in El
+//   imitate <in> <out>     LPC analysis-resynthesis, in El
+//   hear-imitate <sec>     the closed loop: hear a voice, take its signature,
+//                          speak back in it
+//   ingest-audio <wav>     descriptor -> engram node (the capture becomes geometry)
+//   ingest-voice <wav> <n> voiceprint -> engram voice region (how a voice is learned)
+//   converse <manifest>    full-duplex interruptible utterance
+//
+// The descriptors are the point of the afferent half. A capture is NEVER handed
+// on raw: a three-second recording is ~48,000 samples and what leaves this
+// process is eight numbers. That is both the privacy rail (the stream stays
+// local because only its shape travels) and the reason the engram can hold a
+// perception at all — geometry is storable, a waveform is not.
+
+fn cli_usage() -> Bool {
+    println("organ — Neuron's I/O organ, native El (own-core, local, consent-gated)")
+    println("  grant|revoke <camera|mic>     Neuron-level consent")
+    println("  status                        consent + device state")
+    println("  speak <file.wav>              play a WAV aloud (efferent)")
+    println("  tone [hz] [ms]                synthesize and play, no file at all")
+    println("  say <voice> <CODE> [CODE...]  fetch voice FROM THE ENGRAM, render, speak")
+    println("  listen <sec> <out.wav>        mic capture 16k mono (afferent)")
+    println("  see <out.jpg>                 one camera frame (afferent)")
+    println("  wav-info <file.wav>           WAV geometry")
+    println("  feat-audio <file.wav>         compact audio descriptor (8 numbers)")
+    println("  feat-image                    compact scene-geometry from the camera")
+    println("  voiceprint <voice.wav>        F0 + formants F1-F5 (LPC)")
+    println("  imitate <in.wav> <out.wav>    LPC analysis-resynthesis")
+    println("  hear-imitate <sec> <out.wav>  mic -> signature -> imitate -> speak aloud")
+    println("  ingest-audio <file.wav>       descriptor -> engram node (geometry)")
+    println("  ingest-voice <voice.wav> <n>  voiceprint -> engram voice region")
+    println("  converse <manifest.json> [--authority PM] [--barge-at MS[:kind]] [--live-mic] [--resume]")
+    return true
+}
+
+// The engram the organ reads and writes. Its own store, never production's.
+fn cli_engram_dir() -> String {
+    let d: String = env("ORGAN_ENGRAM")
+    if str_eq(d, "") {
+        return "peripheral/.engram"
+    }
+    return d
+}
+
+fn cli_open_engram() -> Bool {
+    let dir: String = cli_engram_dir()
+    fs_mkdir(dir)
+    let ok: Int = engram_store_boot(dir)
+    if ok == 1 {
+        return true
+    }
+    return false
+}
+
+// ── formatting helpers ───────────────────────────────────────────────────────
+
+fn cli_f(v: Float, dec: Int) -> String {
+    return format_float(v, dec)
+}
+
+// ── the descriptor, printed and ingested ─────────────────────────────────────
+//
+// [seconds, sr, ch, rms, peak, zcr, centroid, f0] — the same eight numbers the
+// Swift produced, computed in El, and the compression ratio is the headline:
+// a few dozen bytes standing in for a few hundred kilobytes.
+fn cli_audio_descriptor_text(v: [Float], path: String) -> String {
+    let secs: Float = native_list_get(v, 0)
+    let sr: Float = native_list_get(v, 1)
+    let ch: Float = native_list_get(v, 2)
+    let rms: Float = native_list_get(v, 3)
+    let peak: Float = native_list_get(v, 4)
+    let zcr: Float = native_list_get(v, 5)
+    let cen: Float = native_list_get(v, 6)
+    let f0: Float = native_list_get(v, 7)
+    return "Heard sound (afferent, mic): " + cli_f(secs, 2) + "s at " + cli_f(sr, 0) + "Hz. RMS energy " + cli_f(rms, 4) + ", peak " + cli_f(peak, 4) + ", zero-crossing rate " + cli_f(zcr, 0) + "Hz, spectral centroid " + cli_f(cen, 0) + "Hz, estimated voice pitch F0 " + cli_f(f0, 0) + "Hz. Compact voice/sound signature (8 numbers) — phonetic geometry seed."
+}
+
+fn cli_feat_audio(path: String) -> Bool {
+    let v: [Float] = dsp_compute_audio(path)
+    if native_list_len(v) < 8 {
+        println("{\"ok\": false, \"op\": \"feat-audio\", \"error\": \"cannot read PCM\"}")
+        return false
+    }
+    organ_disclose("FEAT(audio): 8-number signature vs " + int_to_str(float_to_int(native_list_get(v, 0) * native_list_get(v, 1))) + " raw samples.")
+    println("{\"ok\": true, \"op\": \"feat-audio\", \"file\": \"" + path + "\", \"seconds\": " + cli_f(native_list_get(v, 0), 4) + ", \"sample_rate\": " + cli_f(native_list_get(v, 1), 0) + ", \"channels\": " + cli_f(native_list_get(v, 2), 0) + ", \"rms\": " + cli_f(native_list_get(v, 3), 6) + ", \"peak\": " + cli_f(native_list_get(v, 4), 6) + ", \"zcr_hz\": " + cli_f(native_list_get(v, 5), 4) + ", \"centroid_hz\": " + cli_f(native_list_get(v, 6), 4) + ", \"f0_hz\": " + cli_f(native_list_get(v, 7), 4) + "}")
+    return true
+}
+
+fn cli_voiceprint(path: String) -> Bool {
+    let v: [Float] = dsp_voiceprint(path)
+    if native_list_len(v) < 4 {
+        println("{\"ok\": false, \"op\": \"voiceprint\", \"error\": \"cannot read speech\"}")
+        return false
+    }
+    let nf: Int = float_to_int(native_list_get(v, 3))
+    let fs: String = ""
+    let bs: String = ""
+    let i: Int = 0
+    while i < nf {
+        if i > 0 {
+            fs = fs + ", "
+            bs = bs + ", "
+        }
+        fs = fs + cli_f(native_list_get(v, 4 + i * 2), 3)
+        bs = bs + cli_f(native_list_get(v, 5 + i * 2), 3)
+        i = i + 1
+    }
+    println("{\"ok\": true, \"op\": \"voiceprint\", \"file\": \"" + path + "\", \"f0_hz\": " + cli_f(native_list_get(v, 0), 4) + ", \"f0_range\": [" + cli_f(native_list_get(v, 1), 4) + ", " + cli_f(native_list_get(v, 2), 4) + "], \"formants_hz\": [" + fs + "], \"bandwidths_hz\": [" + bs + "]}")
+    return true
+}
+
+// ── main ─────────────────────────────────────────────────────────────────────
+
+fn main() {
+    let a: [String] = args()
+    let n: Int = native_list_len(a)
+    if n < 1 {
+        cli_usage()
+        return
+    }
+    let cmd: String = native_list_get(a, 0)
+
+    // ---- consent -----------------------------------------------------------
+    if str_eq(cmd, "grant") {
+        if n < 2 {
+            println("grant needs a device")
+            return
+        }
+        organ_grant(native_list_get(a, 1))
+        println("{\"ok\": true, \"op\": \"grant\", \"consent\": \"" + organ_consent_status() + "\"}")
+        return
+    }
+    if str_eq(cmd, "revoke") {
+        if n < 2 {
+            println("revoke needs a device")
+            return
+        }
+        organ_revoke(native_list_get(a, 1))
+        println("{\"ok\": true, \"op\": \"revoke\", \"consent\": \"" + organ_consent_status() + "\"}")
+        return
+    }
+    if str_eq(cmd, "status") {
+        println("{\"ok\": true, \"op\": \"status\", \"consent\": \"" + organ_consent_status() + "\", \"speaker\": \"" + speaker_name() + "\", \"speaker_available\": " + int_to_str(speaker_available()) + ", \"mic_os_authorized\": " + int_to_str(mic_available()) + ", \"camera_os_authorized\": " + int_to_str(camera_available()) + "}")
+        return
+    }
+
+    // ---- efferent ----------------------------------------------------------
+    if str_eq(cmd, "speak") {
+        if n < 2 {
+            println("speak needs a wav")
+            return
+        }
+        let ok: Bool = organ_speak_wav(native_list_get(a, 1))
+        println("{\"ok\": " + bool_to_str(ok) + ", \"op\": \"speak\", \"played_aloud\": " + bool_to_str(ok) + "}")
+        return
+    }
+    if str_eq(cmd, "tone") {
+        let hz: Int = 220
+        let ms: Int = 1000
+        if n >= 2 {
+            hz = str_to_int(native_list_get(a, 1))
+        }
+        if n >= 3 {
+            ms = str_to_int(native_list_get(a, 2))
+        }
+        let s: [Int] = organ_tone(hz, ms, 16000)
+        let ok: Bool = organ_speak_samples(s, 16000)
+        println("{\"ok\": " + bool_to_str(ok) + ", \"op\": \"tone\", \"hz\": " + int_to_str(hz) + ", \"ms\": " + int_to_str(ms) + ", \"samples\": " + int_to_str(native_list_len(s)) + ", \"file\": null}")
+        return
+    }
+
+    // ---- the voice, from the engram ----------------------------------------
+    if str_eq(cmd, "say") {
+        if n < 3 {
+            println("say needs <voice> <CODE> [CODE...]")
+            return
+        }
+        cli_open_engram()
+        let vname: String = native_list_get(a, 1)
+        let g: [Int] = organ_voice_fetch(vname)
+        if native_list_len(g) < 6 {
+            println("{\"ok\": false, \"op\": \"say\", \"error\": \"no voice region '" + vname + "' in the engram\"}")
+            return
+        }
+        // Codes and the phoneme map come from the LANGUAGE side. The organ does
+        // not know what a word is and never looks one up.
+        let pmap: [String] = ingest_phonetics("elp/data/phonetics.psv")
+        let codes: [String] = native_list_empty()
+        let i: Int = 2
+        while i < n {
+            codes = native_list_append(codes, native_list_get(a, i))
+            i = i + 1
+        }
+        let voice: [String] = organ_voice_profile(vname, g)
+        let s: [Int] = synth_codes(codes, voice, pmap)
+        let ok: Bool = organ_speak_samples(s, 16000)
+        println("{\"ok\": " + bool_to_str(ok) + ", \"op\": \"say\", \"voice\": \"" + vname + "\", \"f0\": " + int_to_str(native_list_get(g, 0)) + ", \"kf\": " + int_to_str(native_list_get(g, 2)) + ", \"codes\": " + int_to_str(native_list_len(codes)) + ", \"samples\": " + int_to_str(native_list_len(s)) + "}")
+        return
+    }
+
+    // ---- afferent ----------------------------------------------------------
+    if str_eq(cmd, "listen") {
+        if n < 3 {
+            println("listen needs <sec> <out.wav>")
+            return
+        }
+        let secs: Int = str_to_int(native_list_get(a, 1))
+        let out: String = native_list_get(a, 2)
+        if organ_may_listen() == false {
+            println("{\"ok\": false, \"op\": \"listen\", \"error\": \"consent denied (fails closed)\"}")
+            return
+        }
+        organ_disclose("MIC: capturing " + int_to_str(secs) + "s (16 kHz mono, LOCAL, never egresses).")
+        let s: [Int] = mic_capture_pcm16(secs, 16000)
+        let got: Int = native_list_len(s)
+        if got <= 0 {
+            println("{\"ok\": false, \"op\": \"listen\", \"error\": \"capture returned nothing\"}")
+            return
+        }
+        let ok: Bool = write_wav(s, 16000, out)
+        organ_disclose("MIC: captured " + int_to_str(got) + " frames — ready to hand to the ingest organ.")
+        println("{\"ok\": " + bool_to_str(ok) + ", \"op\": \"listen\", \"file\": \"" + out + "\", \"frames\": " + int_to_str(got) + ", \"sample_rate\": 16000}")
+        return
+    }
+    if str_eq(cmd, "see") {
+        if n < 2 {
+            println("see needs an out path")
+            return
+        }
+        if organ_may_see() == false {
+            println("{\"ok\": false, \"op\": \"see\", \"error\": \"consent denied (fails closed)\"}")
+            return
+        }
+        organ_disclose("CAMERA: capturing one frame (LOCAL, never egresses).")
+        let ok: Int = camera_capture_jpeg(native_list_get(a, 1))
+        println("{\"ok\": " + int_to_str(ok) + ", \"op\": \"see\", \"file\": \"" + native_list_get(a, 1) + "\"}")
+        return
+    }
+
+    // ---- descriptors -------------------------------------------------------
+    if str_eq(cmd, "wav-info") {
+        if n < 2 {
+            println("wav-info needs a wav")
+            return
+        }
+        let p: String = native_list_get(a, 1)
+        let w: [Float] = dsp_read_wav(p)
+        if dsp_wav_n(w) <= 0 {
+            println("{\"ok\": false, \"op\": \"wav-info\"}")
+            return
+        }
+        println("{\"ok\": true, \"op\": \"wav-info\", \"sample_rate\": " + int_to_str(dsp_wav_sr(w)) + ", \"channels\": " + int_to_str(dsp_wav_ch(w)) + ", \"frames\": " + int_to_str(dsp_wav_n(w)) + "}")
+        return
+    }
+    if str_eq(cmd, "feat-audio") {
+        if n < 2 {
+            println("feat-audio needs a wav")
+            return
+        }
+        cli_feat_audio(native_list_get(a, 1))
+        return
+    }
+    if str_eq(cmd, "feat-image") {
+        if organ_may_see() == false {
+            println("{\"ok\": false, \"op\": \"feat-image\", \"error\": \"consent denied (fails closed)\"}")
+            return
+        }
+        let f: [Int] = organ_image_descriptor()
+        if native_list_len(f) < 15 {
+            println("{\"ok\": false, \"op\": \"feat-image\", \"error\": \"no frame\"}")
+            return
+        }
+        let grid: String = ""
+        let i: Int = 6
+        while i < 15 {
+            if i > 6 {
+                grid = grid + ", "
+            }
+            grid = grid + int_to_str(native_list_get(f, i))
+            i = i + 1
+        }
+        println("{\"ok\": true, \"op\": \"feat-image\", \"width\": " + int_to_str(native_list_get(f, 0)) + ", \"height\": " + int_to_str(native_list_get(f, 1)) + ", \"mean_rgb\": [" + int_to_str(native_list_get(f, 2)) + ", " + int_to_str(native_list_get(f, 3)) + ", " + int_to_str(native_list_get(f, 4)) + "], \"brightness_pm\": " + int_to_str(native_list_get(f, 5)) + ", \"luma_grid\": [" + grid + "]}")
+        return
+    }
+    if str_eq(cmd, "voiceprint") {
+        if n < 2 {
+            println("voiceprint needs a wav")
+            return
+        }
+        cli_voiceprint(native_list_get(a, 1))
+        return
+    }
+    if str_eq(cmd, "imitate") {
+        if n < 3 {
+            println("imitate needs <in.wav> <out.wav>")
+            return
+        }
+        let s: [Int] = dsp_imitate(native_list_get(a, 1))
+        if native_list_len(s) <= 0 {
+            println("{\"ok\": false, \"op\": \"imitate\"}")
+            return
+        }
+        let ok: Bool = write_wav(s, 16000, native_list_get(a, 2))
+        organ_disclose("IMITATE: rebuilt the voice from its own LPC signature (own-core, no training, no stolen voice).")
+        println("{\"ok\": " + bool_to_str(ok) + ", \"op\": \"imitate\", \"out\": \"" + native_list_get(a, 2) + "\", \"samples\": " + int_to_str(native_list_len(s)) + ", \"method\": \"LPC analysis-resynthesis\"}")
+        return
+    }
+    if str_eq(cmd, "hear-imitate") {
+        if n < 3 {
+            println("hear-imitate needs <sec> <out.wav>")
+            return
+        }
+        let secs: Int = str_to_int(native_list_get(a, 1))
+        let out: String = native_list_get(a, 2)
+        if organ_may_listen() == false {
+            println("{\"ok\": false, \"op\": \"hear-imitate\", \"error\": \"consent denied (fails closed)\"}")
+            return
+        }
+        let heard: String = out + ".heard.wav"
+        organ_disclose("HEAR-IMITATE: open the ear, listen " + int_to_str(secs) + "s, take the voice, speak it back.")
+        let s: [Int] = mic_capture_pcm16(secs, 16000)
+        if native_list_len(s) <= 0 {
+            println("{\"ok\": false, \"op\": \"hear-imitate\", \"error\": \"capture returned nothing\"}")
+            return
+        }
+        write_wav(s, 16000, heard)
+        let re: [Int] = dsp_imitate(heard)
+        if native_list_len(re) <= 0 {
+            println("{\"ok\": false, \"op\": \"hear-imitate\", \"error\": \"could not model the voice\"}")
+            return
+        }
+        write_wav(re, 16000, out)
+        let ok: Bool = organ_speak_samples(re, 16000)
+        println("{\"ok\": " + bool_to_str(ok) + ", \"op\": \"hear-imitate\", \"heard\": \"" + heard + "\", \"out\": \"" + out + "\", \"spoke_aloud\": " + bool_to_str(ok) + "}")
+        return
+    }
+
+    // ---- the afferent wire: descriptor -> geometry --------------------------
+    if str_eq(cmd, "ingest-audio") {
+        if n < 2 {
+            println("ingest-audio needs a wav")
+            return
+        }
+        let p: String = native_list_get(a, 1)
+        let v: [Float] = dsp_compute_audio(p)
+        if native_list_len(v) < 8 {
+            println("{\"ok\": false, \"op\": \"ingest-audio\"}")
+            return
+        }
+        cli_open_engram()
+        let content: String = cli_audio_descriptor_text(v, p)
+        let id: String = engram_node(content, "Observation", 70)
+        engram_store_checkpoint()
+        organ_disclose("INGEST: the capture is now GEOMETRY in the engram (node " + id + ") — the descriptor travelled, the stream did not.")
+        println("{\"ok\": true, \"op\": \"ingest-audio\", \"node_id\": \"" + id + "\", \"content\": \"" + content + "\"}")
+        return
+    }
+    if str_eq(cmd, "ingest-voice") {
+        if n < 3 {
+            println("ingest-voice needs <voice.wav> <name>")
+            return
+        }
+        let p: String = native_list_get(a, 1)
+        let name: String = native_list_get(a, 2)
+        let v: [Float] = dsp_voiceprint(p)
+        if native_list_len(v) < 10 {
+            println("{\"ok\": false, \"op\": \"ingest-voice\", \"error\": \"no voiced frames\"}")
+            return
+        }
+        cli_open_engram()
+        let f0: Int = float_to_int(native_list_get(v, 0))
+        let f1: Int = float_to_int(native_list_get(v, 4))
+        let f2: Int = float_to_int(native_list_get(v, 6))
+        let f3: Int = float_to_int(native_list_get(v, 8))
+        // kf is the vocal-tract scale: this speaker's F1 against the nominal
+        // /AA/ F1 of 730 Hz. One number standing for a tract length.
+        let kf: Int = 1000 * f1 / 730
+        let f0e: Int = f0 * 85 / 100
+        let id: String = organ_voice_ingest(name, f0, f0e, kf, f1, f2, f3, "el-organ-lpc-voiceprint", "COARSE")
+        engram_store_checkpoint()
+        println("{\"ok\": true, \"op\": \"ingest-voice\", \"node_id\": \"" + id + "\", \"name\": \"" + name + "\", \"f0\": " + int_to_str(f0) + ", \"kf\": " + int_to_str(kf) + ", \"f1\": " + int_to_str(f1) + ", \"f2\": " + int_to_str(f2) + ", \"f3\": " + int_to_str(f3) + "}")
+        return
+    }
+
+    // ---- converse ----------------------------------------------------------
+    if str_eq(cmd, "converse") {
+        if n < 2 {
+            println("converse needs a manifest")
+            return
+        }
+        let mf: String = native_list_get(a, 1)
+        let authority: Int = 500
+        let barge: Int = 0 - 1
+        let kind: String = "bargein"
+        let live: Bool = false
+        let resume: Bool = false
+        let i: Int = 2
+        while i < n {
+            let f: String = native_list_get(a, i)
+            if str_eq(f, "--authority") {
+                if i + 1 < n {
+                    authority = str_to_int(native_list_get(a, i + 1))
+                    i = i + 1
+                }
+            }
+            if str_eq(f, "--barge-at") {
+                if i + 1 < n {
+                    let spec: String = native_list_get(a, i + 1)
+                    let c: Int = str_index_of(spec, ":")
+                    if c < 0 {
+                        barge = str_to_int(spec)
+                    } else {
+                        barge = str_to_int(str_slice(spec, 0, c))
+                        kind = str_slice(spec, c + 1, str_len(spec))
+                    }
+                    i = i + 1
+                }
+            }
+            if str_eq(f, "--live-mic") {
+                live = true
+            }
+            if str_eq(f, "--resume") {
+                resume = true
+            }
+            i = i + 1
+        }
+        let plan: [String] = conv_load_manifest(mf)
+        if resume {
+            plan = conv_load_resume()
+            organ_disclose("CONVERSE: resuming — \"as I was saying...\" (" + int_to_str(plan_count(plan)) + " segments left).")
+        } else {
+            organ_disclose("CONVERSE: utterance = \"" + conv_utterance(mf) + "\" (" + int_to_str(plan_count(plan)) + " segments).")
+        }
+        let stopped: Int = conv_run(plan, authority, barge, kind, live)
+        println("{\"ok\": true, \"op\": \"converse\", \"stopped_at\": " + int_to_str(stopped) + ", \"complete\": " + bool_to_str(stopped < 0) + "}")
+        return
+    }
+
+    cli_usage()
+}

peripheral/src/organ_converse.el

@@ -0,0 +1,454 @@
+// organ_converse.el — full-duplex, interruptible speech. The turn-taking organ.
+//
+// WHAT THIS IS FOR. A system that plays an utterance to completion and only
+// then listens is not conversational, it is a loudspeaker with a queue. Being
+// interruptible is not a feature bolted onto speech; it is most of what makes
+// speech social. So the utterance is not a blob of audio — it is an ordered,
+// SALIENCE-TAGGED MEANING-PLAN, and the organ speaks it while listening, decides
+// what to do when interrupted, and can pick the thread back up afterwards.
+//
+// THREE THINGS HAVE TO BE TRUE, and each one is a place naive implementations
+// go wrong:
+//
+//   Barge-in is AT THE SAMPLE. When the mic hears speech, output stops on the
+//   spot — not at the end of the current buffer, not at the end of the segment.
+//   A listener experiences even a fifth of a second of continued talking as
+//   being talked over. This is why the speaker realizer has pause/resume and
+//   reports played_frames: "finish the buffer" is not barge-in.
+//
+//   Yield-or-hold is a DECISION, not a rule. Stopping every time anyone makes a
+//   noise is its own failure — it means Neuron can never finish a sentence that
+//   matters. So the choice is grounded: how salient is what I am mid-saying,
+//   how close am I to done, and how much authority does the interrupter have.
+//   Holding the floor is justified when what I am saying matters AND finishing
+//   is cheap AND the interrupter is not high-priority. Otherwise yield, because
+//   the polite default is the right default.
+//
+//   A backchannel is NOT an interruption. "mm-hm" means keep going. Treating it
+//   as a barge-in makes the system stop every three seconds during ordinary
+//   listening behaviour, which is worse than not listening at all. It is
+//   distinguished by being brief and low-energy: sample again shortly after
+//   onset, and if the speech already died away it was a backchannel.
+//
+// AND THE UTTERANCE SURVIVES. On yield, the remaining plan is persisted, so
+// Neuron can resume — "as I was saying" — instead of losing the thought. An
+// interruption should cost a turn, not the content.
+//
+// The AEC rail: the microphone runs with the OS voice-processing unit enabled
+// so it does not hear our own speaker. Without it Neuron barges in on its own
+// voice on the first syllable and the whole loop is unusable in a real room.
+//
+// Note what is NOT here: nothing about words. A segment carries a `text` field
+// purely as a label for disclosure. The organ speaks pre-rendered audio and
+// never inspects language — that is the language faculty's, and the seam holds.
+
+// ── The meaning-plan ─────────────────────────────────────────────────────────
+//
+// Stored as a flat [String] with stride 3 — file, salience-per-mille, text —
+// because El has no record type and parallel lists drift out of step under
+// editing. Salience is an integer per-mille rather than a Float so the decision
+// arithmetic stays exact and reproducible; a turn-taking decision that varies
+// with floating-point rounding is not one you can debug.
+
+fn plan_new() -> [String] {
+    return native_list_empty()
+}
+
+fn plan_add(plan: [String], file: String, salience_pm: Int, text: String) -> [String] {
+    let p: [String] = plan
+    p = native_list_append(p, file)
+    p = native_list_append(p, int_to_str(salience_pm))
+    p = native_list_append(p, text)
+    return p
+}
+
+fn plan_count(plan: [String]) -> Int {
+    return native_list_len(plan) / 3
+}
+
+fn plan_file(plan: [String], i: Int) -> String {
+    return native_list_get(plan, i * 3)
+}
+
+fn plan_salience(plan: [String], i: Int) -> Int {
+    return str_to_int(native_list_get(plan, i * 3 + 1))
+}
+
+fn plan_text(plan: [String], i: Int) -> String {
+    return native_list_get(plan, i * 3 + 2)
+}
+
+// ── Manifest ─────────────────────────────────────────────────────────────────
+//
+// {"utterance": "...", "segments": [{"file":..., "salience":0.9, "text":"..."}]}
+// Salience arrives as a 0..1 float in the manifest and is converted once, here,
+// at the edge — the same discipline the runtime uses for wire encodings.
+
+fn conv_salience_pm(raw: String) -> Int {
+    // "0.85" -> 850. Parsed by hand rather than through a float so a manifest
+    // typo degrades to a visible number instead of a silent 0.0.
+    let dot: Int = str_index_of(raw, ".")
+    if dot < 0 {
+        let whole: Int = str_to_int(raw)
+        return whole * 1000
+    }
+    let ip: Int = str_to_int(str_slice(raw, 0, dot))
+    let frac: String = str_slice(raw, dot + 1, str_len(raw))
+    let pm: Int = 0
+    let scale: Int = 100
+    let i: Int = 0
+    while i < 3 {
+        let d: Int = 0
+        if i < str_len(frac) {
+            let c: Int = str_char_code(frac, i)
+            if c >= 48 {
+                if c <= 57 {
+                    d = c - 48
+                }
+            }
+        }
+        pm = pm + d * scale
+        scale = scale / 10
+        i = i + 1
+    }
+    return ip * 1000 + pm
+}
+
+fn conv_load_manifest(path: String) -> [String] {
+    let plan: [String] = plan_new()
+    let raw: String = fs_read(path)
+    if str_eq(raw, "") {
+        organ_disclose("CONVERSE: cannot read manifest " + path)
+        return plan
+    }
+    let segs: String = json_get_raw(raw, "segments")
+    let n: Int = json_array_len(segs)
+    let i: Int = 0
+    while i < n {
+        let seg: String = json_array_get(segs, i)
+        let file: String = json_get_string(seg, "file")
+        let text: String = json_get_string(seg, "text")
+        let sal: String = json_get_raw(seg, "salience")
+        let pm: Int = conv_salience_pm(sal)
+        if pm <= 0 {
+            pm = 500
+        }
+        plan = plan_add(plan, file, pm, text)
+        i = i + 1
+    }
+    return plan
+}
+
+fn conv_utterance(path: String) -> String {
+    let raw: String = fs_read(path)
+    return json_get_string(raw, "utterance")
+}
+
+// ── The decision ─────────────────────────────────────────────────────────────
+//
+// Returns: 0 = backchannel, carry on seamlessly
+//          1 = hold the floor ("hang on, let me finish this thought")
+//          2 = yield (stop, let them in)
+//
+// All arguments are per-mille integers. Holding requires BOTH that the material
+// is worth finishing AND that the interrupter is not high-authority — either
+// condition alone is not enough, because "what I'm saying is important" is
+// exactly the reasoning that produces a system nobody can get a word in against.
+fn conv_decide(salience_pm: Int, progress_pm: Int, authority_pm: Int, is_backchannel: Bool) -> Int {
+    if is_backchannel {
+        return 0
+    }
+    let hold_score: Int = (salience_pm * 6 + progress_pm * 4) / 10
+    if hold_score >= 600 {
+        if authority_pm < 800 {
+            return 1
+        }
+    }
+    return 2
+}
+
+// ── Resume ───────────────────────────────────────────────────────────────────
+//
+// The remaining plan, written where a later run can find it. This is what turns
+// an interruption into a pause rather than a loss.
+
+fn conv_resume_path() -> String {
+    let home: String = env("PERIPH_HOME")
+    if str_eq(home, "") {
+        return "peripheral/.resume.json"
+    }
+    return home + "/.resume.json"
+}
+
+// Minimal JSON string escaping. Written here rather than reached for from the
+// runtime because the organ needs exactly two escapes and no dependency: a
+// segment label containing a quote or a backslash must not be able to produce a
+// resume file that fails to parse and silently loses the thread.
+fn conv_escape(s: String) -> String {
+    let n: Int = str_len(s)
+    let out: String = ""
+    let i: Int = 0
+    while i < n {
+        let c: Int = str_char_code(s, i)
+        if c == 34 {
+            out = out + "\\\""
+        } else {
+            if c == 92 {
+                out = out + "\\\\"
+            } else {
+                if c >= 32 {
+                    out = out + str_slice(s, i, i + 1)
+                }
+            }
+        }
+        i = i + 1
+    }
+    return out
+}
+
+fn conv_persist_resume(plan: [String], start_at: Int, reason: String) -> Bool {
+    let n: Int = plan_count(plan)
+    let body: String = "{\"resume_from\": " + int_to_str(start_at) + ", \"reason\": \"" + reason + "\", \"segments\": ["
+    let i: Int = start_at
+    let first: Bool = true
+    while i < n {
+        if first == false {
+            body = body + ", "
+        }
+        body = body + "{\"file\": \"" + plan_file(plan, i) + "\", \"salience\": " + int_to_str(plan_salience(plan, i)) + ", \"text\": \"" + conv_escape(plan_text(plan, i)) + "\"}"
+        first = false
+        i = i + 1
+    }
+    body = body + "]}\n"
+    let ok: Bool = fs_write(conv_resume_path(), body)
+    organ_disclose("CONVERSE: meaning-plan persisted (" + int_to_str(n - start_at) + " segments remain) — Neuron can resume the thread.")
+    return ok
+}
+
+fn conv_clear_resume() -> Bool {
+    return fs_write(conv_resume_path(), "")
+}
+
+// Read a persisted plan back. Salience is already per-mille here (we wrote it),
+// so it is NOT re-scaled — the manifest and the resume file are different
+// formats on purpose, and conflating them silently divides every salience by a
+// thousand.
+fn conv_load_resume() -> [String] {
+    let plan: [String] = plan_new()
+    let raw: String = fs_read(conv_resume_path())
+    if str_eq(raw, "") {
+        return plan
+    }
+    let segs: String = json_get_raw(raw, "segments")
+    let n: Int = json_array_len(segs)
+    let i: Int = 0
+    while i < n {
+        let seg: String = json_array_get(segs, i)
+        plan = plan_add(plan, json_get_string(seg, "file"), json_get_int(seg, "salience"), json_get_string(seg, "text"))
+        i = i + 1
+    }
+    return plan
+}
+
+// ── The loop ─────────────────────────────────────────────────────────────────
+//
+// live_mic  : open the microphone with AEC and let real speech drive barge-in.
+// barge_ms  : if >= 0, inject a barge event at that offset into the utterance
+//             instead. Deterministic, so the decision paths can be exercised
+//             without a room and a person — the same reason periph.swift has it.
+// kind      : "backchannel" or "bargein", for the injected case.
+// authority : interrupter authority, per-mille.
+//
+// Returns the index the utterance stopped at, or -1 if it completed.
+
+fn conv_run(plan: [String], authority_pm: Int, barge_ms: Int, kind: String, live_mic: Bool) -> Int {
+    let n: Int = plan_count(plan)
+    if n <= 0 {
+        organ_disclose("CONVERSE: nothing to say.")
+        return 0 - 1
+    }
+    if speaker_available() == 0 {
+        organ_disclose("CONVERSE: no speaker on this build — cannot hold a conversation.")
+        return 0 - 1
+    }
+
+    let mic_live: Bool = false
+    if live_mic {
+        if organ_may_listen() {
+            let m: Int = mic_monitor_start()
+            if m == 1 {
+                organ_disclose("CONVERSE: full-duplex — mic listening WHILE speaking, AEC on (won't self-interrupt).")
+                mic_live = true
+            }
+            if m == 2 {
+                organ_disclose("CONVERSE: full-duplex — mic listening, but AEC UNAVAILABLE; raising the VAD floor so we do not barge in on ourselves.")
+                mic_live = true
+            }
+            if m == 0 {
+                organ_disclose("CONVERSE: could not open the mic monitor — falling back to injected events.")
+            }
+        }
+    }
+    if mic_live == false {
+        organ_disclose("CONVERSE: deterministic mode (live mic off).")
+    }
+
+    // Without AEC the mic hears the speaker, so the threshold has to sit above
+    // our own output. This is a mitigation and not a fix: the honest note is
+    // that barge-in is markedly less sensitive in this mode.
+    let vad_pm: Int = 20
+    if mic_live {
+        if mic_monitor_start() == 2 {
+            vad_pm = 60
+        }
+    }
+
+    let elapsed_ms: Int = 0
+    let prior_ms: Int = 0
+    let handled: Bool = false
+    // An injected barge is ONE event, not a condition that stays true. Without
+    // this the deadline re-fires on every poll after a backchannel resume, and
+    // the utterance live-locks: paused, resumed, paused again, forever.
+    let injected_fired: Bool = false
+    let i: Int = 0
+
+    while i < n {
+        let file: String = plan_file(plan, i)
+        let sal: Int = plan_salience(plan, i)
+        let frames: Int = wav_frames(file)
+        let rate: Int = wav_rate(file)
+        if frames <= 0 {
+            organ_disclose("CONVERSE: missing or unreadable segment '" + file + "', skipping.")
+            i = i + 1
+        } else {
+            let dur_ms: Int = frames * 1000 / rate
+            organ_disclose("CONVERSE: speaking segment " + int_to_str(i + 1) + "/" + int_to_str(n) + " (salience " + int_to_str(sal) + "/1000) — \"" + plan_text(plan, i) + "\"")
+            let started: Int = speaker_play_wav_async(file)
+            if started == 0 {
+                organ_disclose("CONVERSE: could not start playback for '" + file + "'.")
+                i = i + 1
+            } else {
+                let seg_ms: Int = 0
+                let done: Bool = false
+                let interrupted: Bool = false
+                let speech_ticks: Int = 0
+
+                while done == false {
+                    sleep_ms(10)
+                    seg_ms = seg_ms + 10
+
+                    if speaker_playing() == 0 {
+                        done = true
+                    } else {
+                        // The tick counter is an approximation — each pass costs
+                        // more than the sleep it asked for. The DAC position is
+                        // the truth, so drive the injected deadline off THAT and
+                        // an injected barge lands where it was asked to land.
+                        let pos_ms: Int = speaker_played_frames() * 1000 / rate
+                        elapsed_ms = prior_ms + pos_ms
+                        // --- onset detection: real speech, or an injected event ---
+                        let onset: Bool = false
+                        if mic_live {
+                            let rms: Float = mic_monitor_rms()
+                            let rms_pm: Int = float_to_int(rms * 1000.0)
+                            if rms_pm > vad_pm {
+                                speech_ticks = speech_ticks + 1
+                            } else {
+                                speech_ticks = 0
+                            }
+                            // ~60ms of continuous voice: short enough to feel
+                            // instant, long enough that a door closing is not a turn.
+                            if speech_ticks >= 3 {
+                                if handled == false {
+                                    onset = true
+                                }
+                            }
+                        }
+                        if barge_ms >= 0 {
+                            if injected_fired == false {
+                                if elapsed_ms >= barge_ms {
+                                    onset = true
+                                    injected_fired = true
+                                }
+                            }
+                        }
+
+                        if onset {
+                            handled = true
+                            // (1) BARGE-IN — pause on the spot.
+                            speaker_pause()
+                            let played: Int = speaker_played_frames()
+                            let at_ms: Int = played * 1000 / rate
+                            let progress_pm: Int = at_ms * 1000 / dur_ms
+                            if progress_pm > 1000 {
+                                progress_pm = 1000
+                            }
+                            organ_disclose("CONVERSE: << user speech at " + int_to_str(at_ms) + "ms into segment " + int_to_str(i + 1) + " — PAUSED instantly >>")
+
+                            // (2) backchannel or real barge-in?
+                            let is_bc: Bool = false
+                            if barge_ms >= 0 {
+                                if str_eq(kind, "backchannel") {
+                                    is_bc = true
+                                }
+                            } else {
+                                // Live: look again ~250ms after onset. If the
+                                // energy has already collapsed it was "mm-hm".
+                                sleep_ms(250)
+                                let r2: Float = mic_monitor_rms()
+                                if float_to_int(r2 * 1000.0) < 15 {
+                                    is_bc = true
+                                }
+                            }
+
+                            // (3) yield, hold, or carry on
+                            let d: Int = conv_decide(sal, progress_pm, authority_pm, is_bc)
+                            if d == 0 {
+                                organ_disclose("CONVERSE: read as BACKCHANNEL (\"mm-hm\") — keep going, resume seamlessly.")
+                                handled = false
+                                speech_ticks = 0
+                                speaker_resume()
+                            }
+                            if d == 1 {
+                                organ_disclose("CONVERSE: HOLD the floor — \"hang on, let me finish this thought.\" (salience " + int_to_str(sal) + ", progress " + int_to_str(progress_pm) + ")")
+                                speaker_resume()
+                                // Finish THIS segment, then yield the remainder:
+                                // holding is a request for a moment, not a claim
+                                // on the rest of the conversation.
+                                while speaker_playing() == 1 {
+                                    sleep_ms(20)
+                                }
+                                speaker_stop()
+                                conv_persist_resume(plan, i + 1, "held-then-yield")
+                                if mic_live {
+                                    mic_monitor_stop()
+                                }
+                                return i + 1
+                            }
+                            if d == 2 {
+                                organ_disclose("CONVERSE: YIELD — stop, let them in. Remembering where I was (resumable).")
+                                speaker_stop()
+                                conv_persist_resume(plan, i, "yield")
+                                if mic_live {
+                                    mic_monitor_stop()
+                                }
+                                return i
+                            }
+                        }
+                    }
+                }
+                if interrupted == false {
+                    prior_ms = prior_ms + dur_ms
+                    i = i + 1
+                }
+            }
+        }
+    }
+
+    conv_clear_resume()
+    organ_disclose("CONVERSE: utterance complete (uninterrupted).")
+    if mic_live {
+        mic_monitor_stop()
+    }
+    return 0 - 1
+}