…rite (03-R1/06-M1)

The Claude plugin's SessionEnd `captureMemory()` path wrote a `session_checkpoint`
memory via `akm remember … --force` on every Stop/SubagentStop/PreCompact — a
below-every-improve-gate direct stash write (no judge/confidence/schema gate)
that floods the stash with write-only telemetry. Meta-review 03-R1/06-M1 retires
it. This is the akm-plugin half; the akm-side recombine exclusion filter is
DEFERRED (load-bearing — it excludes all session-capture memories, not just
checkpoints) and the update-stashes cron is a separate akm PR.

Deleted (claude/hooks/akm-hook.ts): `captureMemory()` + its 3 call sites, the
`capture-memory` CLI subcommand, helpers used only by it, and the now-dead
Stop/SubagentStop/PreCompact hook registrations (their only command was
`capture-memory …`). `akm index` on session-end survives — relocated into
`sessionEnd()` under the same AKM_INDEX_ON_SESSION_END/akmAvailable gates.

PRESERVED (verified by code-review): the memory-CANDIDATE pipeline
(extractCandidatesFromText/appendCandidates/CANDIDATE_LOG → /akm-memory-promote),
the `akm extract` SessionEnd path, and `tagRecalledContent` (the injection-
hardening banner — NOT captureMemory-specific; wraps all recalled/curated
content). Reviewer fixes applied: dropped the now-unused `redactObject` import;
corrected the stale "harvest session memories at stop/compact time" README line.

Tests: removed ~13 captureMemory/session_checkpoint tests; added 3 covering the
relocated sessionEnd→index (runs index, respects opt-out, asserts no `remember`).

Evals: the tier-2 `memory` metric replayed session logs through the now-deleted
`capture-memory session-end`, so it's removed (metric + fixtures + diff policy
rules + docs) and the checked-in baseline regenerated via `baseline:update` (5
metrics, no `memory`). Latency drift in the regen is harmless — latency is
opt-in (`--include-latency`), not gated by default.

Gate: `bun test tests/` 319/0; `tier2/runner.ts --baseline` exit 0 (no regression).

Follow-ups (out of scope): opencode/index.ts has its own parallel
session_checkpoint write (sibling plugin); the recombine filter + live crontab
removal + build/reinstall (~beta.59) remain.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018YjU1mGiShdDP4qFW7p4mv