## What Problem This Solves
Retires Matrix state imports whose last shipped JSON writers predate the July 2026 migration support window.
## User Impact
Upgrades from pre-July-2026 versions are no longer migrated: Matrix `thread-bindings.json` and `startup-verification.json`. Doctor and the affected runtime preserve those files and explain how to upgrade through OpenClaw 2026.9.5: run Doctor, start Matrix once to import them, then install the latest release.
July and newer SQLite bindings, verification cooldowns, device metadata, token-root selection, and schema upgrades remain supported. Public plugin SDK compatibility and other Matrix migrations are unchanged.
## Why This Change Was Made
Both file writers ended in `84a965a1a2` on May 30. The last confirmed stable JSON writer, `v2026.5.28`, was published May 30; `v2026.5.30-beta.1` first shipped SQLite on May 31, followed by stable `v2026.6.1` on June 3. Inspection of `v2026.7.1` confirms the same SQLite namespaces and keys, with no JSON rewrite or restoration path. The 2026.9.5 bridge retains both runtime imports.
Deletes JSON decoding, merging, import-marker stores, cleanup writes, and the obsolete thread-binding JSON root score. The plugin owns the source-preserving refusal; existing Doctor ordering and schema migration ownership stay intact. Net production reduction: 140 lines.
Other channel config aliases remain: supported July config rewrites can still preserve them. Separate owner follow-ups will cover independently proven formats.
## Evidence
- Independent isolated review: no actionable findings through P2.
- Matrix runtime/storage/Doctor boundary tests passed, including July-shaped binding keys and verification cooldowns, unchanged retired-file bytes, and archive exclusion.
- The intact shipped `v2026.7.1` account SQLite fixture upgraded through the actual Doctor CLI; canonical rows and archived database bytes remained intact.
- Doctor state/config migration suites passed. Plugin contracts: **1,132 tests / 48 files passed**.
- `node scripts/check-changed.mjs` passed; both `check-madge-import-cycles.ts` and `check-import-cycles.ts` report **0**.
- Linux single-worker wall measurements (`pnpm test <file> --maxWorkers=1`): Doctor import contract **2.89s**, storage **29.49s**, bindings **15.10s**, startup verification **13.73s**. No new process boot, timer, retry, or weakened assertion was added.
Proof used an isolated AWS checkout pinned to the base and byte-verified candidate patch. Hosted CI will validate the pushed head. Release history and retention decisions were checked separately from test execution.