fix(desktop): branch snapshots keep pre-compaction history, isolated from parent (salvage #76286)

[teknium1]

Salvages the separable branch-snapshot half of PR #76286 (@DannyFengTianYu): branches now snapshot the complete pre-compaction display transcript, and branch transcripts are isolated from parent turns added after the fork. The PR's competing display-dedupe scheme (excluded by #86595) is NOT carried.

Changes (cherry-picked, authorship preserved)

57c51cc401 — isolate branch transcripts from parent updates

• hermes_state.py: explicit /branch sessions (durable _branched_from marker) own a copied transcript, so lineage walks (get_messages_as_conversation(include_ancestors=True), get_resume_conversations, get_ancestor_display_prefix) no longer pull the live parent's rows into the branch — messages written to the original after the fork stop leaking into the branch view. Compression continuations keep full lineage reads.
• Conflict resolved toward main: the function bodies were rebased onto today's _read_ctx() connection pattern (the PR predated that refactor); _is_explicit_branch_session uses _read_ctx too.

cb671285ee (from c3d2d759ae) — preserve complete history when branching

• tui_gateway/methods_session.py (session.branch): the live in-memory history is the model projection — after compaction it holds only a summary + protected tail. The branch seed now reads the persisted display projection (get_resume_conversations), reconciled with the live tail via main's existing _reconcile_display_with_live, so the child no longer permanently loses every turn archived before the fork. Falls back to the in-memory history when the DB read fails.
• Conflict resolutions toward main + contributor intent:
  • _visible_branch_history keeps full message rows instead of the PR's minimal {role, content} copies — main's copy loop preserves reasoning fields and timeline-marker tags (display_kind/display_metadata, [Bug]: Desktop plain-Enter submit silently deleted ~65 messages — stale truncate_before_user_ordinal + auto-attached confirm_truncate (3rd occurrence after #70516, #80763) #82756); the PR's slimming would have silently dropped them (caught by main's test_session_branch_keeps_reasoning_fields).
  • The PR's test ProfileDB gained append_messages_batch (main's bounded-chunk write path from perf(session): batch SQLite writes into single transaction per flush #23254).
  • Renderer hydration uses getAllSessionMessages (paged, include_compacted=true) instead of the PR's pre-fix(desktop): salvage compaction transcript-visibility cluster — surface archived turns + preserve running-session transcripts (#67871) #86595 getSessionMessages single call, so the hydrated prefix includes compaction-archived rows and isn't capped at one page.
  • selectBranchMessages' comparable-text helper inlines the @image: directive strip (the PR's textWithoutImageRefs export from its excluded commits doesn't exist on main).
• apps/desktop/.../use-session-actions/: whole-chat branch prefers the authoritative persisted transcript; branching from a clicked bubble maps it by durable row id first, same-role/text ordinal as fallback, and keeps the local prefix when unmappable; context-drift abort if the route/selection/runtime changes during hydration.

Excluded from #76286 (per #86595's exclusion notes)

• 0bd0f57331 + 04f6c5e147 — the hermes_state.py display-projection filtering / legacy-replay disambiguation and tui_gateway/server.py + use-message-stream reconciliation. This is the second, competing display-dedupe scheme that fix(desktop): salvage compaction transcript-visibility cluster — surface archived turns + preserve running-session transcripts (#67871) #86595's include_compacted + (role, content, timestamp, …) dedupe already covers; carrying both would ship two overlapping dedupe layers on the same read path.

Validation

Check	Result
tests/test_tui_gateway_server.py + tests/test_hermes_state.py	806 passed, 1 pre-existing failure (test_search_projection_skips_context_enrichment_queries) reproduced identically on clean origin/main
Desktop vitest: use-session-actions.test.tsx, use-session-actions/utils.test.ts	152 passed
npx tsc --noEmit (apps/desktop)	clean
scripts/audit_pr_attribution.py	all contributor emails mapped

Credit: @DannyFengTianYu (#76286) — both commits cherry-picked with authorship preserved.

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[github-actions]

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_{ran on c9a5fe1 — chore: map contributor email (audit_pr_attribution)}

⚠️ Warnings

OSV vulnerability scan · View job

5 known vulnerabilities found in pinned dependencies.

• CVE-2026-67213 in package-lock.json
• CVE-2026-67213 in website/package-lock.json
• CVE-2026-70608 in package-lock.json
• CVE-2026-56876 in package-lock.json
• CVE-2026-70606 in package-lock.json

How to fix:

Review the findings in the Security tab. Update the affected dependencies if a patched version is available.

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debug info

CI timings

CI timings · View report · View job

Wall time 16m35s vs 15m19s (+8.3%). 16 job(s) slower, 17 faster, 4 unchanged.

• Python tests / Run tests slice 11/12: +23.0s
• Python tests / Run tests slice 3/12: +17.0s
• Python tests / Run tests slice 4/12: +16.0s
• Python tests / Run tests slice 2/12: -14.0s
• Python tests / Run tests slice 12/12: +14.0s