diff --git a/lang/runtime/el_runtime.c b/lang/runtime/el_runtime.c
index 021f3f9..fc5e7a2 100644
--- a/lang/runtime/el_runtime.c
+++ b/lang/runtime/el_runtime.c
@@ -14379,7 +14379,67 @@ el_val_t engram_ise_log_append(el_val_t content_v){
         }
     }
     fputs("\"}\n", f);
+    /* RETENTION (2026-08-17 self-review). The on-graph ISE branch in
+     * server.el calls engram_prune_telemetry(48h) on every insert, but that
+     * branch is DEAD in production: ENGRAM_ISE_OFFGRAPH=1 is the live
+     * setting, so every state event lands here instead — and this path had
+     * no retention of any kind. Measured: 17.1 MB / 14,305 events over 3.56
+     * days = 4.81 MB/day, growing without bound (~1.76 GB/year). The graph
+     * got its telemetry-growth fix on 2026-07-16; moving telemetry off-graph
+     * moved the leak rather than closing it.
+     *
+     * Byte-bounded rather than time-bounded on purpose: this is a flat
+     * append-only file with no index, so size is the property that actually
+     * has to be bounded, and a byte check is O(1) against the handle we
+     * already hold (ftell) instead of an O(file) timestamp scan per append.
+     * At the measured rate the 64 MB default retains ~13 days — comfortably
+     * more history than the 48h the on-graph path kept.
+     *
+     * Compaction keeps the TAIL, never the head: engram_dreams_json reads
+     * the last ~2 MB of this file for dream-recall, so the recent end is the
+     * end that has a reader. KEEP is held well above that 2 MB window so
+     * recall is never truncated by a rotation. The honesty rail is
+     * preserved exactly as before — rotated-out remains "I don't remember",
+     * never a synthesized dream; this only makes the forgetting bounded and
+     * explicit instead of deferred forever. */
+    long pos = ftell(f);
     fclose(f);
+    {
+        long maxb = 64L*1024L*1024L;
+        long keepb = 16L*1024L*1024L;
+        const char* mv = getenv("ENGRAM_ISE_LOG_MAX_BYTES");
+        if (mv && *mv) { long v = atol(mv); if (v > 0) maxb = v; }
+        if (keepb > maxb/2) keepb = maxb/2;
+        if (pos > 0 && pos > maxb) {
+            FILE* rf = fopen(path, "rb");
+            if (rf) {
+                if (fseek(rf, pos - keepb, SEEK_SET) == 0) {
+                    char* buf = (char*)malloc((size_t)keepb + 1);
+                    if (buf) {
+                        size_t rd = fread(buf, 1, (size_t)keepb, rf);
+                        buf[rd] = 0;
+                        /* Resume at the first LINE boundary so the tail never
+                         * begins with a half-written JSON record. */
+                        char* start = memchr(buf, '\n', rd);
+                        start = start ? start + 1 : buf;
+                        size_t keep_n = rd - (size_t)(start - buf);
+                        char tmp[4096];
+                        snprintf(tmp, sizeof tmp, "%s/state-events.jsonl.tmp", dir);
+                        FILE* wf = fopen(tmp, "wb");
+                        if (wf) {
+                            int ok = (fwrite(start, 1, keep_n, wf) == keep_n);
+                            fclose(wf);
+                            /* Only replace the live log if the tail was written
+                             * in full — a short write must not destroy history. */
+                            if (ok) rename(tmp, path); else remove(tmp);
+                        }
+                        free(buf);
+                    }
+                }
+                fclose(rf);
+            }
+        }
+    }
     return EL_INT(1);
 }