chore: remove old handoff docs, plans, review reports, and task lists from rootHEADmain

Removed 40+ markdown files that were cluttering the repo root:
- frontend-*-handoff.md (28 files) — historical API contract handoffs, features all implemented
- backend-to-fe-handoff.md, backend-to-fe-handoff-2.md — old handoff docs
- broken-chat-repair-handoff.md — old repair handoff
- PLAN-mcp.md, PLAN-per-edit-diagnostics.md — old planning docs
- ai-review-report.md, crash-review-report.md — one-time review reports
- tasks.md, HANDOFF.md — outdated status docs (git log is the source of truth)

Kept: AGENTS.md, GLOSSARY.md, ORCHESTRATOR.md, README.md
Also: gitignored ai-review-report.md so future Gemini reviews don't commit it

1 files changed, 0 insertions, 67 deletions

diff --git a/frontend-metrics-pass2-handoff.md b/frontend-metrics-pass2-handoff.md
deleted file mode 100644
index adf0404..0000000
--- a/frontend-metrics-pass2-handoff.md
+++ /dev/null
@@ -1,67 +0,0 @@
-# FE handoff — persisted replay metrics (Pass 2) + metrics endpoint
-
-> **Courier doc** (backend → `../frontend`, via the user). Per ORCHESTRATOR §7
-> the backend does NOT write the FE repo; the FE orchestrator applies this delta
-> on its side (regenerate the in-repo `.dispatch/*.reference.md` snapshots + bump
-> the `file:` dep). `lsp references` does not span the two repos. Backend commit:
-> `6db12ff`.
-
-## Versions
-- `@dispatch/wire` `0.3.0 → 0.4.0` (additive)
-- `@dispatch/transport-contract` `0.3.0 → 0.4.0` (additive)
-
-Pure-type, additive change — no breaking edits to existing types.
-
-## New wire types (`@dispatch/wire`, re-exported by `@dispatch/transport-contract`)
-
-```ts
-interface StepMetrics {
-  stepId: StepId;          // `<turnId>#<index>`, join key to the live stream
-  usage: Usage;            // { inputTokens, outputTokens, cacheReadTokens?, cacheWriteTokens? }
-  ttftMs?: number;         // time to first token (optional — clock + first-token gated)
-  decodeMs?: number;       // first token → stream end
-  genTotalMs?: number;     // stream start → end (== ttftMs + decodeMs when a first token was seen)
-}
-
-interface TurnMetrics {
-  turnId: string;          // plain wire turn id, join key to AgentEvents
-  usage: Usage;            // aggregate across all steps
-  durationMs?: number;     // turn wall-clock (optional — clock gated)
-  steps: readonly StepMetrics[];  // per-step, in step order
-}
-```
-
-These are the **persisted, replayable** counterparts of the live `usage` /
-`step-complete` / `done` events (which remain transient and unchanged).
-
-## New read endpoint
-
-`GET /conversations/:id/metrics` → `ConversationMetricsResponse`:
-
-```ts
-interface ConversationMetricsResponse { turns: readonly TurnMetrics[] }
-```
-
-Semantics:
-- `turns` = every **sealed** turn's `TurnMetrics`, in **turn-append order**.
-- A turn appears only **after seal** (post-persist); an in-flight/unsealed turn is absent.
-- This is a **separate axis** from `GET /conversations/:id?sinceSeq=` (which returns
-  seq-cursor chunk CONTENT). Metrics are keyed per **turn**, not per chunk, so they are
-  **not** seq-filtered — hence a sibling route, not a field on the history response.
-- Unknown / metric-less conversation → `{ turns: [] }`.
-- CORS: same wildcard as the other routes.
-
-## Suggested FE consumption
-On (re)opening a conversation, the chat feature can `GET /conversations/:id/metrics`
-once alongside the history hydrate (`?sinceSeq=`), then render historical
-tokens/latency per turn (and per step via `stepId`) — identical fields to what it
-already routes from the live `step-complete` / `usage` / `done` stream. TPS is
-still derived FE-side (`usage.outputTokens / decodeMs`); context-size proxy =
-`usage.inputTokens`.
-
-## Invariants (confirmed live)
-- Persisted `TurnMetrics.usage` / `durationMs` and each `StepMetrics`
-  (`stepId` + `usage` + `ttftMs`/`decodeMs`/`genTotalMs`) **byte-match** what the
-  live stream emitted for the same turn (verified end-to-end against flash).
-- `stepId` is the SAME value on the live `step-complete`/`usage` events, the persisted
-  `StepMetrics`, and the tool chunks — one grouping key across live + replay.