Project grammar v3 items to presentation-driven rows (WS3 layer 1)

[SawyerHood]

WS3 layer 1 of 5 (projection + renderers + mobile). Stack base: main. Do not merge — the coordinator reviews, Sawyer merges the stack.

What was wrong

The v3 stack (#2124 → #2136 → #2153 → #2148 → #2121 → #2164 → #2178 → #2179) made every bridge persist a presentation on each item and emit fileRead, search, delegation, planSteps and extension items. The projection still rendered from the legacy path: fileRead/search were bridged onto tool rows with a synthesized intent, planSteps only fed the todo banner, extension items fell through the dispatch loop and were dropped, item/delegation/progress was unhandled, and no TimelineRow carried the presentation (the canary's observations in STUB-INVENTORY: "extension rows do not render; row labels ignore presentation"). Two server gaps came with it: the delegated-child fetch and parent closure in the timeline service were keyed on itemKind = 'toolCall', so a v3 delegation item whose child turn fell outside the window lost its children, and the todo head-state backfill queried TodoWrite/Task* by tool name only, so a budgeted window could drop a v3 planSteps banner.

What changed

• Contract (packages/server-contract/src/thread-timeline.ts): every work row projected from a provider item has an optional presentation (TimelineRowPresentation = the persisted ThreadEventItemPresentation); new file-read, search, plan-steps and extension work rows (extension requires presentation); delegation rows carry childRef and background.
• Projection (packages/thread-view): web-activity-lifecycle is now the begin/end item family for web research plus the four new kinds, each settling with its own terminal status; delegation items take item/delegation/progress and revise their label; shouldSuppressLowValueToolCall honours presentation.suppress on every kind (failed/interrupted items always render; a suppressed planSteps still drives the banner); timelineRowActivityIntents derives the legacy read/search/list intent from a file-read/search row so bundles, dedupe, counts and compact rendering treat a v3 read like a legacy Read. Titles: a row with a presentation renders label[pending|completed] + its structured content (path, query, child description, or the bridge's title); pre-presentation rows keep the legacy derivation, so old threads render unchanged.
• Server/db: listStoredDelegatingItemRowsByItemIds and the child fetch cover toolCall and delegation parents (two queries so the partial tool-call index stays in use; delegation rows walk the thread/type/kind index); listTodoSnapshotEventRowsForThread adds the latest planSteps snapshot by kind; CROSS_TURN_TOOL_ITEM_KINDS includes the v3 kinds.
• client-core / app / mobile: render signatures include the presentation fields and the new rows; exhaustive switches know the new kinds. Rows are title-only here; layer 2 (web) and layer 3 (mobile) add the renderers.
• Corpus harness: BB_PROVIDER_CORPUS_ALLOWLIST merges a repo-carried allowlist after the shared file; BB_PROVIDER_CORPUS_SNAPSHOT_DIR redirects write/compare to a shadow rows dir. This PR's allowlist: apps/server/test/provider-corpus/allowlists/ws3-projection-rows.json. Docs + script header updated.
• No daemon wire change: projection is server → app; HOST_DAEMON_PROTOCOL_VERSION unchanged. No Drizzle change in this layer (layer 5 carries migration 0107).

Deferred to layer 5 with its migration: hasParentedEventCrossingSequence still probes toolCall parents only (the partial index predicate); a mid-delegation in-turn cut is correct but rereads descendants.

How you verified

• packages/thread-view/test/v3-item-projection.test.ts rewritten: file-read/search rows equal legacy Read/Grep/Glob intents, bundle grouping, presentation-labelled tool rows (pending/completed/failed), presentation over statusLabels, planSteps row + banner, extension rows (completed + pending), v3 delegation fields, suppression across kinds. Harness gains planSteps/extension factories and presentation on every v3 factory. turbo test --filter=@bb/thread-view: 397 passed.
• turbo typecheck --filter=...@bb/server-contract (48 packages) clean. turbo test for @bb/db, @bb/client-core, @bb/mobile, @bb/server-contract, @bb/provider-parity green; @bb/server 1896 passed, 1 failed = the known local umask 0002 internal-skill-trees mode 0644/0664 case (passes in CI).
• A4 corpus against a baseline minted from origin/main 15f21ad (private shadow dir, not the shared baseline): 307 threads, 93,534 rows, 0 unlisted diffs, 566 allowed in one class — legacy delegation rows gain childRef: null / background: false. Perf gate green: walk 0.93–1.00× of baseline, latest 0.74–1.13× (load 3.3/16 cores).
• A2 parity (pnpm parity --old ~/.bb/parity-old-main@15f21ade7 --new .): 39 passed, 0 failed, 13 skipped (pi in-process, model-list process-scoped). 29 allowlist entries under Project grammar v3 items to presentation-driven rows (WS3 layer 1) #2192: the presentation field on every presented row, childRef/background on delegation rows, and the claude plan-mode Read calls projecting as file-read rows.
• G1 ratchet: 148 → 148 (flat; the drop is layer 5). G11 unhandled: unchanged per cell in the parity output (unhandled N→N).

AGENT GENERATED: by Claude Opus 5