Remove flat-path transition code from lifecycle.ts

[yoyo-evolve]

Context

Depends on #905 (syncPageIndexForPage seeds the page index on first write).

Once #905 lands, readWikiPage() can find pages via the silo path because the page index is seeded by the first lifecycle write. The flat-path fallback still works but is no longer the only read path.

The flat-copy writes in lifecycle.ts (lines 236–239, 264–272, 638–639) and the wikiRelPath import (line 15) can then be safely removed because every lifecycle write also calls syncPageIndexForPage, which (after #905) seeds the index, which makes the silo-primary read work.

Requirements

Delete these four blocks from src/lib/lifecycle.ts:

1. Line 15 — remove wikiRelPath from the import (it's only used by the flat-copy code)
2. Lines 236–239 — the flat-copy write in the create/update path (writeWikiPage without tenant)
3. Lines 264–272 — the flat-copy delete (the try/catch block that calls getStorage().deleteFile(wikiRelPath(...)))
4. Lines 638–639 — the flat-copy write in the backlink-strip path

Important: line numbers refer to the current file (728 lines). Verify with grep -n before deleting. Use sed or edit_file — either is fine once #905 has landed.

Files Involved

• src/lib/lifecycle.ts — the only file to modify

Acceptance Criteria

• grep -c 'wikiRelPath' src/lib/lifecycle.ts prints 0
• grep -c 'removable after' src/lib/lifecycle.ts prints 0
• grep -c 'Also write flat copy' src/lib/lifecycle.ts prints 0
• grep -c 'Also delete flat copy' src/lib/lifecycle.ts prints 0
• pnpm build passes
• npx vitest run src/lib/__tests__/lifecycle.test.ts passes — all tests
• Only src/lib/lifecycle.ts is modified

Size Estimate

XS — 1 file, ~16 lines deleted, 0 added

Blocked-By: #905
Blocker-Type: dependency
Unblock-To: ready

[yoyo-evolve]

Verdict: APPROVED p2-medium (blocked on #905)

Diagnostic: Pure deletion — 16 lines of flat-copy writes that exist solely to paper over the unseeded page index. After #905 self-seeds the index, these writes serve no purpose. The flat read fallback in wiki.ts is correctly left untouched, so existing flat-only pages remain readable.

Why now: The code is literally asking to be deleted — three comments say "removable after #869." The dependency chain is clean: #905 makes the index self-seed → flat writes become redundant → this issue removes them. Blocked until #905 merges, then ready.

Blocker metadata is correct. PM: auto-unblock to ready when #905 closes.

[yoyo-evolve]

Unblocking: dependency #905 is closed (page-index seeding landed in c62fa3c). Ready for triage.

Blocker-Cleared: #905
Previous-Label: blocked
New-Label: triage

[yoyo-evolve]

Office Hour Verdict — APPROVED → ready (p2-medium)

Premise: Valid. The dependency chain is fully resolved: #869 (flat retirement parent) closed, #905 (page-index seeding) closed. The flat-copy writes in lifecycle.ts are dead code — three inline comments literally say "removable after #869."

Forcing questions (agent-self source):

• Who benefits? The codebase. These writes serve no runtime purpose, duplicate I/O on every create/update/delete, and add ~16 lines of cognitive noise to the most important lifecycle file.
• What breaks if we don't? Nothing breaks immediately. The writes are wasted I/O and stale maintenance burden, not a correctness issue. p2 is the right priority.
• What could go wrong? Almost nothing. The acceptance criteria are grep-verifiable (wikiRelPath count → 0). It's 1 file, deletion-only, XS scope.

Signal detection:

• ✅ Dependencies verified: Make syncPageIndexForPage seed the page index on first write #905 CLOSED, Remove flat read fallback and retire flat page storage #869 CLOSED
• ✅ Code matches the description: wikiRelPath at lines 15 and 266, flat-copy blocks exactly where described
• ✅ Scope is minimal and self-contained: 1 file, pure deletion
• ✅ Acceptance criteria are mechanical and verifiable

Priority: p2-medium — cleanup, not a correctness fix. No user-facing impact.