feat(server): run-mirror — engine stream routed by turn-owning session, mid-run switching isolated - #32
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Port PR #22's run-mirror semantics to the current architecture so a mid-run session switch never leaks live engine lines into another session's view or persisted record (ticket session-isolation/02). An earlier partial implementation on this branch introduced the per-(cid, engine sid) runChat buffer family in state-bus.js and routed all six stream-write sites in streamAcpPrompt through r.chatArray(). This commit completes the port after review; the buffer family and the always-buffer write routing were kept, the following gaps were fixed: - Live view: with every write landing in the buffer, the wire snapshots still shipped cs.chat only, so the owning session's own view never saw its turn stream. state-bus now exposes runChatViewChat / snapshotViewFields and every snapshot builder (three SSE push sites, /api/state, the SSE first frame, the switch response) re-attaches the buffer for the owning view and scopes the run indicator to the viewed session: a foreign turn renders as idle in the switched-to view, and the owning view keeps its running claim even after a switch's resetContext healed it (projected from the run registry, no cs mutation). - Finalize clobbers: streamAcpPrompt's finalize re-pointed cs.mcodeSessionId and wrote the engine binding + title through whichever record cs pointed at after a mid-run switch, redirecting the switched-to session onto the run's engine conversation. The turn's owning webui record id is now captured at send time and passed through runMcodeAcp; all cs mutations are gated on still viewing the owning session, and the record-side binding/title writes address the owning record by id. - Draft promotion: bindDraftToMcodeSid promoted records through cs and would rename or merge the switched-to session's record when the engine session id arrived after a switch. A pre-bind switch now uses the new bindRecordToMcodeSid helper (promoteDraftToMcodeSid targeted at a record id, no cs access). - Finalize drain: handleSend drains the buffer after the run settles — appending to cs.chat when the user still views the owning session (the ● rewrite then lands on the drained line) or writing the lines to the owning session's persisted record via the new appendChatToSession helper when they switched away; the viewed session's chat and record stay clean either way. Failed and empty turns flush the same way. - createRunChat now replaces the cid's buffer map: beginRun allows one live turn per cid, so a session/load fallback that re-keys the buffer cannot leave a stale entry behind. Tests: new routes/chat-run-mirror.check.mjs drives the real chat.js → runMcodeAcp → sessions.js → state-bus chain plus the real switch route against a fake ACP transport and pins mid-run switch isolation, view merging, record attribution, and first-turn draft promotion under a pre-bind switch. stream-cumulative-render.test.js — whose three failures were caused by the new buffer routing — now reads the routed lines through runChatLinesFor. helpers/_setup.js mirrors the three new sessions.js exports. Regenerated release/public-source.json for the new test file. Verified live on an isolated instance (server 18098 + web 18099, MCODE_WEBUI_DATA_DIR in a temp dir, fake slow multi-tool engine): session A streaming → switch to B mid-run shows no A lines and an idle indicator; switching back shows the record plus the live buffered lines with the running indicator; after completion the full turn persisted to A's record (B stayed at zero lines). Gates: pnpm typecheck (0 errors), webui suites (190 relevant tests ×3 runs green; full suite 1258 pass with only lib/mcode-acp-note.test.js hanging at teardown — reproduced on clean HEAD, environmental), pnpm test:webapp (213 pass), pnpm build.
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What
Ports PR #22's run-mirror semantics to the current architecture, closing the verified defect where switching/creating sessions mid-run leaked live streamed lines into the switched-to view and persisted the turn into the wrong draft record.
state-bus.js): per(cid, engine sid)buffers;streamAcpPromptroutes all 6 stream-write sites through an explicit chatTarget (chatArray()— buffer when the viewed session differs from the turn's owner, elsecs.chat).cs.chatwhen still viewing the owner, elseappendChatToSession(owning record); sid/binding/title writes are gated on still-viewing (no post-switch clobbering); failed/empty turns flush too.bindRecordToMcodeSid(record-targeted) — a pre-bind switch can no longer promote/merge the wrong record.Compatibility (regression-checked)
Acceptance (independent agent, REAL engine)
PASS — all 5 ticket criteria live-verified: mid-run switch shows zero leaked lines + idle indicator; switch-back mid-run shows the merged record+live buffer with the running indicator; finalize lands the complete turn in the owner's record only; multi-session cycles and 409s clean. The dev's own live self-check additionally caught and fixed 4 gaps in the inherited code (broken live-view snapshots, finalize clobbers, wrong-record promotion, missing drain). Gates: typecheck 0 · chat-run-mirror 3/3 ×3 · stream-cumulative-render adapted tests pass · test:webapp 213/213 · build ✓ · check:source ✓.
Known decisions/notes: DELETE-mid-run discards buffered content silently ("delete wins" — appendChatToSession returns false for a missing record); a second window (different cid) viewing a running session sees DB-committed lines grow but an idle indicator (cid-keyed run registry — the same-cid semantics this ticket targets are correct). Follow-up ticket 07 (transport-level result.answer accumulation) remains queued.
Full
pnpm verifydeferred to CI (includes main's post-#31 test-teardown fixes on merge).