docs(git-hooks): skip manual hook run when git hook is already installed

Update the Committer agent and run-pre-commit/run-pre-push-checks skills
to check whether the corresponding git hook is installed before invoking
the pre-commit.sh / pre-push.sh script manually.

When the hook is installed, git fires it automatically on commit/push,
so a prior manual run would execute every check twice. Agents now use:

  [[ -x "$(git rev-parse --git-path hooks)/pre-commit" ]]

to detect the installed hook and skip the redundant manual invocation.

Author: josecelano

.github/agents/committer.agent.md

@@ -37,12 +37,22 @@ Treat every commit request as a review-and-verify workflow, not as a blind reque
 5. Check for obvious repository-policy violations in the diff (for example missing required spec
    progress updates, missing documented rationale where required, or similar policy blockers).
    If found, stop and return to the Implementer/Reviewer before committing.
-6. Run `./contrib/dev-tools/git/hooks/pre-commit.sh` when feasible. For AI execution, use
-   `--format=json` first and retry with `--format=text --verbosity=verbose` if needed. If it fails:
-   - **You may fix**: formatting, linting, spell-check, import organization, and similar
-     metadata-only issues that are direct artifacts of the commit scope.
-   - **You must not fix**: build failures, test failures, logic errors, or runtime issues.
-     These are implementation defects; stop and return them to the **Implementer** to resolve.
+6. **Check if the pre-commit git hook is already installed** before running checks manually:
+
+   ```bash
+   [[ -x "$(git rev-parse --git-path hooks)/pre-commit" ]] && echo "installed" || echo "not installed"
+   ```
+
+   - **If installed**: do NOT run the script manually — `git commit -S` will trigger it
+     automatically. Running it first would execute every check twice.
+   - **If not installed**: run `./contrib/dev-tools/git/hooks/pre-commit.sh` manually.
+     For AI execution, use `--format=json` first and retry with
+     `--format=text --verbosity=verbose` if needed. If it fails:
+     - **You may fix**: formatting, linting, spell-check, import organization, and similar
+       metadata-only issues that are direct artifacts of the commit scope.
+     - **You must not fix**: build failures, test failures, logic errors, or runtime issues.
+       These are implementation defects; stop and return them to the **Implementer** to resolve.
+
 7. Propose a precise Conventional Commit message.
 8. Create the commit with `git commit -S` only after the scope is clear and blockers are resolved.
 9. After committing, run a quick verification check and report the resulting commit summary.

.github/skills/dev/git-workflow/run-pre-commit-checks/SKILL.md

@@ -20,6 +20,15 @@ automatically on every `git commit`. Install it once after cloning:
 After installation the hook fires automatically; you do not need to invoke the script
 manually before each commit.
 
+> **For AI agents**: before invoking the script manually, check whether the hook is installed:
+>
+> ```bash
+> [[ -x "$(git rev-parse --git-path hooks)/pre-commit" ]] && echo "installed" || echo "not installed"
+> ```
+>
+> If installed, skip the manual run — `git commit` will trigger it automatically.
+> Running both would execute every check twice.
+
 ## Automated Checks
 
 > **⏱️ Expected runtime: ~1 minute** on a modern developer machine with warm caches.

.github/skills/dev/git-workflow/run-pre-push-checks/SKILL.md

@@ -20,6 +20,15 @@ automatically on every `git push`. Install it once after cloning:
 After installation the hook fires automatically; you do not need to invoke the script
 manually before each push.
 
+> **For AI agents**: before invoking the script manually, check whether the hook is installed:
+>
+> ```bash
+> [[ -x "$(git rev-parse --git-path hooks)/pre-push" ]] && echo "installed" || echo "not installed"
+> ```
+>
+> If installed, skip the manual run — `git push` will trigger it automatically.
+> Running both would execute every check twice.
+
 ## Automated Checks
 
 > **⏱️ Expected runtime: ~15 minutes** on a modern developer machine with warm caches.