[Juliusolsson05]

Problem

The renderer's live entry window (#375) is capped at 2,000 entries / 32 MiB per session, but the two-day performance journal shows renderer.session.memory.entries at 5,016 (1,924 samples over the cap) and one session's ghostMap at 917. Full evidence in #724.

Cause: computeProtectBound lowered the trim bound to the updatedAt of every un-superseded ghost, orphaned or not, while the 1 s sweep only ever removed superseded ghosts. One orphan that JSONL never matches (every sidecar-shaped stream, for instance) pinned the bound for the rest of the session — planLiveEntryTrim returned null on every burst and runtime.entries became append-only. The ghost map itself also grew monotonically.

What changed

The render predicate's rule 4 (ghostPredicate.ts, mirrored in mergedEntries.ts) already defines a ghost that can never paint again: orphaned and at-or-before lastJsonlEntryAt, which only moves forward. This PR makes the two other consumers of the ghost map agree with that definition instead of changing it:

• liveEntryWindow.ts: new isGhostHiddenBehindJsonlTail; computeProtectBound skips those ghosts; planLiveEntryTrim takes lastJsonlEntryAt as an optional fourth argument (null keeps the previous behaviour, so existing callers and tests are unchanged).
• ghosts.ts: new gcHiddenOrphanGhosts reducer, reference-stable on no-op, that evicts exactly that set once the ghost has been orphaned for GHOST_SUPERSEDED_GC_MS (the orphan transition already persisted it to the ghost log).
• useIpcSubscriptions.ts: the sweep chains the new reducer after gcSupersededGhosts; the JSONL-burst trim passes the post-burst tail; the ghost_orphan_sweep feed-debug record gains evictedCount.

Not changed, deliberately (see the Warning section of docs/design/ghost-system.md): rules 1–5, the orphan TTL, orphanStale, gcSupersededGhosts, and therefore which ghosts render. Orphans newer than the JSONL tail — the stuck-JSONL fallback — still pin the bound and still stay in the map.

Linked issues

Fixes #724. Refs #375 (the window this restores), #103, #365.

Verification

• NODE_ENV=test npx vitest run --project unit src/renderer/src/session-runtime/ src/renderer/src/workspace/ — 33 files, 391 tests passed. New contracts in entries.test.ts (hidden orphan no longer bounds the trim; an orphan newer than the tail still does; a null tail keeps today's behaviour) and a new ghosts.test.ts for gcHiddenOrphanGhosts (evicts only orphaned, un-superseded, at-or-before-tail ghosts after the grace; keeps orphans ahead of the tail, un-orphaned ghosts, everything with a null tail; leaves superseded ghosts to the existing reducer; reference-stable).
• --project renderer for the same directories — passed.
• npx tsc -b --pretty false — clean.
• After: renderer.session.memory.entries should plateau at the cap and ghostMap should stop growing on the next long run.

Known limitations

• A hidden orphan is evicted only once the JSONL tail passes it; a session whose JSONL is genuinely stuck keeps its orphans, which is the intended fallback.
• Mixed-clock caveat is unchanged from rule 4: renderer wall-clock updatedAt against a producer JSONL timestamp.

Plan: docs/superpowers/plans/2026-09-03-orphan-ghosts-unpin-trim.md.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Kk16MNVJtWAnCeGxGRuHqa

[Juliusolsson05]

Self-review pass (adversarial review of the first cut) — resolved in HEAD:

• Re-mint hazard (should-fix): ghostsFromSemanticTurn re-creates any missing block of semantic.currentTurn, so evicting a hidden orphan of the live turn would resurrect it un-orphaned. gcHiddenOrphanGhosts now takes the current turn id and skips those ghosts; unit test added.
• Layering: isGhostHiddenBehindJsonlTail moved into ghosts.ts; liveEntryWindow.ts imports it (no cycle).
• Grace boundary now inclusive like gcSupersededGhosts; orphanedAt hoisted; sweep debug summary names evictions; typo fixed.
• Design doc: new Eviction of hidden orphans section, lifecycle diagram, orphan-TTL/IPC-wiring bullets, and the Warning now lists all three orphanedAt consumers.
• Integration test: useIpcSubscriptions.renderer.test.tsx drives mint → orphan → history roll-off → over-cap JSONL burst trims → sweep evicts, end to end (fails on main: no trim).

Noted for follow-up issues rather than this PR: the same re-mint hazard exists in gcSupersededGhosts, and session.ts re-appends the whole ghost log on every resume.