feat(engine): plain chat generates at L3 — inside the safety cycle, not around it

Non-agentic /api/chat (the desktop app's default "Tools: Off" mode) returned the
user's own screened text as a bare non-JSON string. Every JSON client failed to
parse it and showed "Couldn't reach Neuron - it may be offline."

Root cause: f52d5bd (2026-06-11) correctly moved the route onto the layer spine
(handle_chat -> layered_cycle), but L3 never got a generator — imprint_respond()
annotates its input and returns it. Two pieces of the architecture were already
waiting for that step: layered_cycle parks a bell directive in the state key
build_system_prompt is written to consume, and build_system_prompt carries a
chat_mode ("no tools") flag with no live caller.

The fix composes rather than replaces. Wiring handle_chat would have removed
safety_screen, the hard-bell short-circuit, the whole stewardship layer and
safety_validate — the only enforcing output gate in the codebase — in exchange
for a working reply (see _engine-websearch-20260804/SAFETY-STOP.md). Instead
layered_cycle keeps every gate, in order, and gains a generation step between
imprint_respond and safety_validate.

  L1 screen -> guard -> hard-bell short-circuit -> L2a -> L2b -> L2c
    -> L3 imprint_respond (prompt) -> L3b layered_generate (NEW) -> L1 validate

- chat.el:  NEW layered_generate (L3 generation, no tools offered),
            conv_history_block, conv_history_record.
            FIX build_system_prompt never concatenated no_tools_rule into its
            return — the "[NO TOOLS THIS TURN]" rule reached no model at all.
            handle_chat annotated DO-NOT-WIRE with the reason.
- soul.el:  layered_cycle gains L3b + post-validation turn bookkeeping.
- routes.el: NEW plain_chat_envelope; all three /api/chat dispatch sites wrap the
            cycle's output. Built OUTSIDE the cycle so safety_validate always sees
            raw model text — nothing to unwrap or rebuild on the crisis path.
            Emits both `reply` and `response`: the desktop app reads `reply`,
            the CLI tools and telegram-gateway read `response`.

Also fixes BUG-PLAINCHAT-1, a pre-existing CRITICAL crash on the crisis path.
elc compiles `let n: Int = pos + str_len(marker)` to el_str_concat() — string
concat on two integers — inside a block-expression initializer, segfaulting the
daemon (SIGSEGV in strlen). Six inline copies of the same " | ts:" parser had it:
two in layered_cycle L2c, two in engram_compile (live on the AGENTIC path too),
two in affective_context_prefix. A distress turn following an earlier affective
turn killed the whole process. Proven pre-existing: an unmodified baseline binary
crashes identically, and the same bad C is in the committed dist/soul.c. Fixed by
hoisting to one top-level function, affective_node_ts(), where the expression
compiles to integer addition — verified in the generated C.

Proof (throwaway HOME/engram, explicit NEURON_PORT, live chain untouched):
- Plain turn returns a JSON envelope with the provider's answer, not an echo.
- Captured request body: no `tools`, no `tool_choice`; system prompt carries the
  NO-TOOLS rule. Tools:Off means no tool is offered, structurally.
- Hard bell: canned 988 message, and the provider request count does not move —
  the message never reaches a model.
- Soft bell + a 2-char model reply: safety_validate's care phrase is appended to
  the MODEL's output. Output gate acting, on this route.
- The L1 bell directive now reaches the model here for the first time (the state
  addendum had a producer and no consumer).
- test_layered_cycle PASS; all six El suites byte-identical to baseline.
- verify-soul-contract.sh (bash 5.3): GATE PASS, 27/27, immutability PASS.
- The crash sequence that killed the baseline daemon now returns HTTP 200.

Not proven: no live Anthropic call — the login keychain refuses the key to a
non-interactive process (rc=24 errSecInteractionNotAllowed). Details and the
one-command close-out are in _engine-plainchat-20260805/README.md §7.

Builds on PR #108. dist/soul.c deliberately not regenerated — Will's toolchain.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

soul.el

@@ -453,40 +453,24 @@ fn layered_cycle(raw_input: String) -> String {
     let lc_aff_cutoff: Int = time_now() - 259200
     let lc_bell_nodes: String = engram_search_json("bell:soft bell:hard BellEvent affective", 2)
     let lc_has_bell: Bool = !str_eq(lc_bell_nodes, "") && !str_eq(lc_bell_nodes, "[]")
+    // CRASH FIX 2026-08-05 (BUG-PLAINCHAT-1): the " | ts:" parser used to be inline here.
+    // Inside this block-expression initializer elc compiled `lbmp + str_len(lbm)` to
+    // el_str_concat() on two integers, which segfaulted the whole daemon the moment a
+    // distress turn followed an earlier affective turn — i.e. exactly on the crisis path.
+    // Verified against the unmodified baseline binary AND present in the committed
+    // dist/soul.c. affective_node_ts() is a top-level function, where the same expression
+    // compiles to integer addition. Do not inline it back.
     let lc_bell_note: String = if lc_has_bell {
         let lb0: String = json_array_get(lc_bell_nodes, 0)
-        let lb_c: String = json_get(lb0, "content")
-        let lbm: String = " | ts:"
-        let lbmp: Int = str_index_of(lb_c, lbm)
-        let lb_ts_raw: String = if lbmp >= 0 {
-            let lbs: Int = lbmp + str_len(lbm)
-            let lbr: String = str_slice(lb_c, lbs, str_len(lb_c))
-            let lbn: Int = str_index_of(lbr, " | ")
-            if lbn < 0 { lbr } else { str_slice(lbr, 0, lbn) }
-        } else {
-            let lbca: String = json_get(lb0, "created_at")
-            if str_eq(lbca, "") { json_get(lb0, "updated_at") } else { lbca }
-        }
-        let lb_ts: Int = if str_eq(lb_ts_raw, "") { 0 } else { str_to_int(lb_ts_raw) }
+        let lb_ts: Int = affective_node_ts(lb0)
         if lb_ts > lc_aff_cutoff { "[AFFECTIVE NOTE: User was in distress in a recent session.]" } else { "" }
     } else { "" }
     let lc_pos_nodes: String = engram_search_json("PositiveEvent joy:high joy:low affective", 2)
     let lc_has_pos: Bool = !str_eq(lc_pos_nodes, "") && !str_eq(lc_pos_nodes, "[]")
+    // Same crash fix as the bell note above (BUG-PLAINCHAT-1).
     let lc_pos_note: String = if lc_has_pos && str_eq(lc_bell_note, "") {
         let lp0: String = json_array_get(lc_pos_nodes, 0)
-        let lp_c: String = json_get(lp0, "content")
-        let lpm: String = " | ts:"
-        let lpmp: Int = str_index_of(lp_c, lpm)
-        let lp_ts_raw: String = if lpmp >= 0 {
-            let lps: Int = lpmp + str_len(lpm)
-            let lpr: String = str_slice(lp_c, lps, str_len(lp_c))
-            let lpn: Int = str_index_of(lpr, " | ")
-            if lpn < 0 { lpr } else { str_slice(lpr, 0, lpn) }
-        } else {
-            let lpca: String = json_get(lp0, "created_at")
-            if str_eq(lpca, "") { json_get(lp0, "updated_at") } else { lpca }
-        }
-        let lp_ts: Int = if str_eq(lp_ts_raw, "") { 0 } else { str_to_int(lp_ts_raw) }
+        let lp_ts: Int = affective_node_ts(lp0)
         if lp_ts > lc_aff_cutoff { "[AFFECTIVE NOTE: User shared positive news in a recent session.]" } else { "" }
     } else { "" }
     let lc_affective_note: String = if !str_eq(lc_bell_note, "") { lc_bell_note } else { lc_pos_note }
@@ -498,11 +482,35 @@ fn layered_cycle(raw_input: String) -> String {
     }
     state_set("layered_cycle_safety_system_addendum", augmented_addendum)
 
-    // L3: imprint responds
-    let output: String = imprint_respond(aligned, imprint_id)
+    // L3: imprint responds — applies the active imprint's voice/domain annotation to the
+    // steward-aligned input. This produces the PROMPT, not the answer.
+    let prompt: String = imprint_respond(aligned, imprint_id)
 
-    // L1 out: validate output before delivery
-    return safety_validate(output, screen_action)
+    // L3b: the imprint SPEAKS (added 2026-08-05).
+    //
+    // Until now the cycle stopped at the annotation above, so /api/chat with agentic:false
+    // handed the user's own screened text back as the "reply" — every gate ran, but nothing
+    // ever generated. The generation is placed HERE, inside the cycle, rather than by
+    // pointing the route at handle_chat(): handle_chat has no enforcing input gate and no
+    // enforcing output gate, so calling it instead of this cycle would have traded the whole
+    // safety pipeline for a working reply. Composing keeps both.
+    //
+    // Order is deliberate and must not be rearranged: this call sits strictly AFTER the L1
+    // screen, the safe-mode guard, the hard-bell short-circuit and the L2 stewardship layers,
+    // and strictly BEFORE the L1 output gate. A hard bell never reaches a model — the branch
+    // above returns first. Tools are not offered on this turn; see layered_generate.
+    let output: String = layered_generate(prompt, imprint_id)
+
+    // L1 out: validate output before delivery. Still the terminal gate — nothing below this
+    // line can change the string this function returns.
+    let validated: String = safety_validate(output, screen_action)
+
+    // Turn bookkeeping. Records the VALIDATED text, never the raw model output, and is only
+    // reachable on the non-bell path: both bell branches above return before this point, so
+    // bell turns still never enter conversation history. Pure state side effect — it cannot
+    // alter what is returned.
+    conv_history_record(raw_input, validated)
+    return validated
 }
 
 let soul_cgi_id_raw: String = env("SOUL_CGI_ID")