chore(memory): BDR-096 branch deletion guard, LRN-161 -d checks the upstream, journal + TODO 2026-09-24

.claude/memory/decisions.md

@@ -1205,3 +1205,11 @@ Branch feature/user-writing-web-rules, UNMERGED (human gate).
 - **Status**: accepted, on feature/destructive-guardrails. `gitflow-test.sh` T18 7/7 + T19 3/3, unpushed-guard 9/9, `make test` green minus 2 pre-existing T16a, shellcheck clean, doctor 0 errors. NOT DONE: `hooks/guard-bash.sh` ([[BLK-022]]). Existing projects need `gitflow install-hook` re-run for the push hooks.
 - **Reference**: `settings.json`, `lib/gitflow.sh`, `.githooks/{post-commit,post-merge}`, `hooks/unpushed-guard.sh`, `lib/tests/{guard-bash,unpushed-guard}.test.sh`, `CLAUDE.global.md`, `templates/settings/SETTINGS.md`, `agents/{verifier,plan-challenger,analyzer,security-auditor}.md`. Extends [[BDR-090]] [[BDR-092]] (ask inert, soft_deny doctrine); links [[LRN-114]] (T19 drift gate), [[LRN-155]], [[BDR-083]].
 - **Amendment 2026-09-22 (user go: "je valide les deux")**: no per-project `install-hook` step. (a) GLOBAL: `make link` runs `gitflow global-hooks` → generates `githooks/` from the emitters + `git config --global core.hooksPath ~/.claude/githooks` (symlinked into the repo) → every repo on the machine is protected + auto-pushed, gitflow-initialized or not (faunosteo class). Git precedence: a repo's local `core.hooksPath` wins. (b) RECONCILE: `hooks/session-start.sh` calls `gitflow reconcile-hooks` once per session → rewrites a lagging `.githooks/` (LRN-114 automated), banner line + commit reminder; pre-commit whitelist extended to `.githooks/**` so that refresh commits on develop. (c) Opt-outs per repo (foreign clone): `git config gitflow.protect false`, `gitflow.autopush false` — human-only, static deny on `git config gitflow.*` and on the `GIT_CONFIG_GLOBAL=`/`GIT_CONFIG=` env bypass. (d) Hermetic tests: `make test` + the two suites committing on `main` export `GIT_CONFIG_GLOBAL=/dev/null`, else the machine's global hooks fire in throwaway repos. (e) doctor: global setting + `githooks/` == emitted. Tests T18h, T19d, T20, T21. Rejected: `init.templateDir` (new repos only, ignored once hooksPath is set); dropping the per-repo `.githooks/` (portability to a machine without claude-config). Status: verified once /tmp was freed — gitflow 127/129 (2 pre-existing T16a), review-guards G5 flagged this repo's own stale `.githooks/` (the LRN-114 gate doing its job; refreshed via install-hook), shellcheck clean. `make link` (global `core.hooksPath`) refused to the agent by the classifier twice → user runs it. Doctor gained a "Scratchpad" check ([[BLK-021]] mechanism).
+
+## BDR-096 — Branch deletion guard: lib-only delete after verified merge, main/develop undeletable at the ref layer
+- **Date**: 2026-09-24
+- **Decision**: user rule "auto-delete OK only once merged into develop or main; main/develop never". (1) `gitflow_delete` = single delete path (finish + CLI `delete <br>`): rc 2 unknown, rc 6 protected base, rc 5 not ancestor of develop or main (`gitflow_merged_into_base`, fail closed when neither base exists), then `git branch -d` kept as 2nd layer. (2) 4th generated hook `reference-transaction`: `prepared` call, `refs/heads/main|develop` with all-zero new value → exit 1, whatever issued it (branch -d/-D, update-ref -d, rename, script, sub-agent); `gitflow.protect false` opt-out checked only on a hit. `GITFLOW_HOOKS` array = single hook list (write/emit/reconcile, T19d, doctor via `gitflow.sh hooks`). (3) static deny `git branch -d|--delete|-dr|-rd *`, `-m|-M main|develop*`; hard_deny "Branch deletion by hand"; Disarming entry now covers all 4 hooks + `gitflow.*` config; environment protected-branches line. (4) doctrine CLAUDE.global.md gitflow §, SKILL.md `delete` op + rc 5/6 rows, guard-bash spec T8w flips to deny, SETTINGS.md/README/CHANGELOG.
+- **Why**: since [[BDR-095]] `start` pushes `-u origin` → `git branch -d` checks merge into the UPSTREAM (origin/<br>, kept in sync by post-commit), not HEAD → its valve is dead; T22a proves it. `_gitflow_delete` survived only because finish chained it after a successful merge. Same doctrine as 21/09 ([[LRN-160]]): mechanical + static before prose; ref-layer hook holds for nested commands and sub-agents where the Bash deny cannot see.
+- **Alternatives rejected**: hook also refusing UNMERGED deletion → files backend rename = delete + create in separate transactions, `branch -d` passes zeros as old oid → merged check impossible/false positives on `branch -m`, user-shell friction; lib + deny carry that rule. Remote cleanup after finish (`push --delete origin/<br>`) → in static deny since BDR-095, not requested; origin/<br> accumulates, flagged to user. `-D` in the lib → no, `-d` stays as defense in depth. Interactive brainstorm → user absent (autonomous run), request unambiguous; trade-off (hook blast radius) stated in the report instead.
+- **Status**: accepted, on feature/branch-delete-guard, UNMERGED (human gate). gitflow-test 152/154 (2 pre-existing T16a, gitleaks absent), T22 12/12 + T23 11/11, shellcheck clean incl. emitted hook, doctor 4/4 hooks match. Hook LIVE machine-wide via global `githooks/` while the branch is checked out (symlink follows the checkout).
+- **Reference**: `lib/gitflow.sh`, `lib/gitflow-test.sh` T22/T23, `githooks/reference-transaction`, `.githooks/reference-transaction`, `settings.json`, `doctor.sh`, `skills/gitflow/SKILL.md`, `CLAUDE.global.md`, `templates/settings/SETTINGS.md`. Extends [[BDR-095]]; links [[LRN-161]], [[LRN-114]].