docs: add PR-race, self-merge, and fresh-worktree-hook learnings

Signed-off-by: Sebastian Mendel <info@sebastianmendel.de>

Author: CybotTM

skills/git-workflow/references/git-hooks-setup.md

@@ -142,3 +142,27 @@ against the repo root, before inspecting it.
   `/dev/null` — is portable to Windows) and `git push --no-verify`. Never
   make the bypass the default; fix the hook environment or commit from the
   primary checkout when possible.
+
+### Fresh worktree: missing deps and stale `hooksPath`
+
+A freshly-created worktree often breaks pre-commit/pre-push hooks — and can even
+abort the worktree creation itself:
+
+- It has no `vendor/`/`node_modules`, so a hook binary (`vendor/bin/grumphp`,
+  `captainhook`, a husky script) is missing.
+- A stale or broken `core.hooksPath` points at a nonexistent binary in **another**
+  worktree.
+
+Either failure aborts worktree-add, commits, and pushes. Bypass cleanly and
+**scoped** — don't disable hooks globally:
+
+```bash
+git -c core.hooksPath=/dev/null commit -s ...   # scoped to this one command
+git push --no-verify
+```
+
+(`core.hooksPath="$(mktemp -d)"` is the Windows-portable equivalent — see the
+controlled-bypass note above.) CI is authoritative for these repos (see "Hooks
+Are Fast Feedback — CI Is the Gate"), so a scoped bypass here is safe. Also: in a
+fresh worktree, `Read` a file before `Write`/`Edit` — there is no cached state
+for a path the tooling has not seen yet.

skills/git-workflow/references/pull-request-workflow.md

@@ -1018,6 +1018,41 @@ Other ruleset rules to expect: `required_approving_review_count`, `required_revi
 > about merge-readiness — see the Merge-Gate Command above plus this ruleset
 > call. Discovering gates one round-trip at a time is the anti-pattern.
 
+## Self-Authored PR Merge (Permission Classifier)
+
+When you drive your own PR to merge (e.g. via `/pr-finish`), the auto-mode
+permission classifier blocks self-merges and admin self-bypass — a self-authored
+merge is treated as requiring a human. Do **not** attempt the merge twice and
+then bounce to the human; two denials read as stalling.
+
+- Recognize up front that finishing a self-authored PR will hit the classifier,
+  and settle the merge path **before** starting.
+- For archive/cleanup tasks, take the local-clone + signed-commit + PR path from
+  the start — not a Contents-API commit or an admin bypass the classifier will
+  reject.
+- If a human merge is genuinely required, ask **one** structured question up
+  front rather than discovering the block via two denials.
+
+## Shared-Account and Parallel-Job PR Races
+
+When several agent jobs run under the **same** git/GitHub identity (a shared
+bot/CI account), a PR can be force-pushed or merged out from under your review or
+take-over by a parallel job — and you cannot prove your own job didn't do it.
+Defend:
+
+1. **Snapshot head + merge state** at the start of any review/take-over, and
+   re-check immediately before acting; abort or rebase if it moved:
+
+   ```bash
+   gh pr view <NUMBER> --json headRefOid,state,mergeStateStatus
+   ```
+
+2. **Never trust a pre-existing shared worktree** for review/fix — a parallel job
+   may churn or delete it mid-task. Create your own isolated worktree off a
+   freshly-fetched `origin/main`.
+3. **`gh pr diff` vs the file you `Read` disagree?** The branch was force-pushed
+   between calls — re-fetch and re-derive from the committed state on origin.
+
 ## Signed Commits with Rebase Merge
 
 ### The Problem