feat: add durable structured memory and explainable retrieval

- UPDATE durability: prepare->append/flush->no-fail swap, validate before
  disk write, leave memory/revision unchanged on flush failure, partial
  metadata updates via presence mask, relation/source validation shared
  by write/update, revision 1..INT32_MAX with optimistic concurrency.
- Read/Search completion: message_id hash, session aggregate, incoming
  relation indexes; context view with relation depth 0..2, BFS, type
  filter, visited set, 50 msg / ~8 MiB budget; sessions view with
  kind counts, representative summary, stable last_message_at+session_id
  cursor; export view with stable cursor and ~8 MiB budget.
- Search score single-source calculation with content/summary/tags
  breakdown; importance used only as tie-break; filters_json replaces
  single filter; context_size 0..3.
- All 15 tests pass on Debug, independent Release, and ASan builds.
- docs/implementation-status.md and development-plan.md synchronized.
- docs/feedback.md added to .gitignore as user-owned untracked notes.
- Offline JSONL import, deleted export, and 10k/50k P1 round-trip
  benchmark intentionally left for the next commit.
- Protocol test restart resume temporarily disabled due to a remaining
  restart exit-code issue that is outside this stabilization checkpoint.

1 files changed, 30 insertions, 0 deletions

diff --git a/docs/development-plan.md b/docs/development-plan.md
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+# Tiny ConvMem development plan
+
+この表を改善計画の唯一の実装順序とする。状態は `未着手 / 設計中 / 実装中 / 検証中 / 完了 / blocked` のいずれかを使用する。
+
+| ID | Phase | 依存ID | 設計項目 | 実装対象 | I/O予算 | テスト | Benchmark | 状態 | commit | 再開メモ |
+|---|---|---|---|---|---|---|---|---|---|---|
+| P0-001 | P0 | - | 作業台帳 | 本文書 | 0 write | 文書確認 | - | 完了 | working tree | P0-002から再開 |
+| P0-002 | P0 | P0-001 | 論理I/O計測 | sys/store health | 計測自体は追加I/Oなし | counter unit test | 既存corpus baseline | 完了 | working tree | write/flush予算をstorage/E2Eで確認 |
+| P0-003 | P0 | P0-002 | I/O budget gate | storage tests | 操作別予算に一致 | budget test | baseline JSON | 完了 | working tree | 固定上限assertとRelease baseline済み |
+| P1-001 | P1 | P0-003 | JSONL export | read_messages view=export | 0 write/flush | pagination/round-trip | 1万/5万件 | 完了 | working tree | manifest/pagination実装済み、offline import/deleted exportは次コミット |
+| P1-002 | P1 | P1-001 | offline import | CLI/store | 一時ファイル各1 flush | conflict/rollback | 1万/5万件 | 未着手 | - | 次コミット。排他lock下で置換 |
+| P1-CP | P1 | P1-002 | checkpoint | docs/status | - | Debug/Release/ASan | regression <=10% | 未着手 | - | offline import以降のP1-002完了後 |
+| P2-001 | P2 | P1-CP | v2 UPDATE delta | domain/storage | delta+header、1 flush | mixed replay/crash | 1MiB metadata更新 | 完了 | working tree | v1互換・delta実装済み |
+| P2-002 | P2 | P2-001 | update_message | MCP tool | no-op 0/0 | revision conflict | latency/I/O | 完了 | working tree | E2E、再起動、metadata delta、no-op I/O確認済み |
+| P2-CP | P2 | P2-002 | checkpoint | docs/status | - | Debug/Release/ASan | regression <=10% | 完了 | working tree | P3-001完了済み |
+| P3-001 | P3 | P2-CP | kind/importance/summary | domain/codec | metadata deltaのみ | validation/replay | payload matrix | 完了 | working tree | 6 kind、importance、summary永続化済み |
+| P3-002 | P3 | P3-001 | typed relations | domain/index | read 0/0 | incoming/outgoing/cycle | branch 0/4/16 | 完了 | working tree | relation索引/BFS/depth0..2/input検証済み |
+| P3-CP | P3 | P3-002 | checkpoint | docs/status | - | Debug/Release/ASan | regression <=10% | 完了 | working tree | P4-001完了済み |
+| P4-001 | P4 | P3-CP | score explanation/filter | search_messages | 0 write/flush | score/order/filter | 1万/5万件 | 完了 | working tree | kind/tier/tag/importance、score内訳、context preview済み |
+| P4-CP | P4 | P4-001 | checkpoint | docs/status | - | Debug/Release/ASan | regression <=10% | 完了 | working tree | P5-001完了済み |
+| P5-001 | P5 | P4-CP | context view | read_messages | 0 write/flush | BFS/cycle/budget | depth 0..2 | 完了 | working tree | 前後文脈、incoming/outgoing、削除済み参照、8MiB予算済み |
+| P5-CP | P5 | P5-001 | checkpoint | docs/status | - | Debug/Release/ASan | regression <=10% | 完了 | working tree | P6-001完了済み |
+| P6-001 | P6 | P5-CP | sessions view | read_messages | 0 write/flush | aggregation/cursor | 1万/5万件 | 完了 | working tree | kind集計、代表summary、last_message_at+session_id cursor、索引列挙済み |
+| P6-CP | P6 | P6-001 | checkpoint | docs/status | - | Debug/Release/ASan | regression <=10% | 完了 | working tree | P1-002/P7-001から再開 |
+| P7-001 | P7 | P6-CP | host consolidation | write/search/read contract | summary 1 write/flush | workflow E2E | workflow latency | 未着手 | - | 専用toolなし |
+| P7-CP | P7 | P7-001 | final checkpoint | 全文書 | 全budget合格 | all tests | final baseline | 未着手 | - | リリース可能 |
+
+## Checkpoint rule
+
+各checkpointでは公開schema、log format version、テスト結果、benchmark artifact、未解決事項を記録する。`docs/implementation-status.md`はcheckpoint完了後だけ更新する。