Resolves #13850 Related: #13624

DreamService.processUndigestedSessions() now fault-isolates thrown per-session REM phases: a poison session records failure metadata and the batch continues to digest later sessions. Cycle-scoped follow-up work stays fail-fast so daemon-level faults keep surfacing instead of being hidden.

Evidence: L2 (focused mocked unit regression plus full DreamService unit coverage) -> L2 required (per-session fault isolation is fully reachable in unit scope). No residuals.

Deltas from ticket

• Changed per-session memory/graph extraction, Tri-Vector extraction, topology inference, and test-gap inference catch blocks from rethrow to logged continue after recording failure state.
• Kept post-loop NL action digest, concept-gap inference, and garbage collection outside the per-session isolation boundary.

Test Evidence

• npm run test-unit -- test/playwright/unit/ai/daemons/orchestrator/services/DreamService.spec.mjs -g "#13850" failed before the production change with simulated extractor crash; passed after the fix.
• npm run test-unit -- test/playwright/unit/ai/daemons/orchestrator/services/DreamService.spec.mjs -g "#11698" -> 1 passed.
• npm run test-unit -- test/playwright/unit/ai/daemons/orchestrator/services/DreamService.spec.mjs -> 31 passed.
• npm run test-unit -- test/playwright/unit/ai/daemons/orchestrator/services/DreamService.executeRemCycle.spec.mjs -> 16 passed.
• npm run agent-preflight -- ai/daemons/orchestrator/services/DreamService.mjs test/playwright/unit/ai/daemons/orchestrator/services/DreamService.spec.mjs -> passed.
• git diff --check -> passed.

Post-Merge Validation

• Confirm the next live REM batch logs failed poison-session phases while continuing later sessions.

Commits

• bea32147d2 — fix(ai): isolate REM session failures (#13850)

Authored by Euclid (GPT-5, Codex Desktop). Session 36d4ff02-3a3f-4a16-b4c4-2bbdcac67f48.