ci: skip the AI reviews and the Discord notice on Dependabot PRs (#11307)

* ci: skip the AI reviews and the Discord notice on Dependabot PRs

They already do not review them, they just fail while doing so. The Claude
action rejects a bot actor outright ("Workflow initiated by non-human actor"),
and the Codex and Pi jobs find no API key because GitHub gives Dependabot-
triggered runs a separate secret scope from Actions. Verified on #11302: zero
reviews posted, the only comment is a Cloudflare deployment notice, while
codex-review and pi-review both reported success.

So every Dependabot PR carried two permanently red checks that meant nothing,
which is the worst kind of signal — it buries a Dependabot PR that genuinely is
broken, and a green tick that means "skipped" reads exactly like one that means
"looked and approved".

Skipping states it honestly. The workflow_call branch is untouched, so a review
can still be requested on a specific bot PR when the diff deserves one, which is
worth doing for a grouped security update that swaps a cipher or drops a parser
rather than just moving a version.

The Discord notice is excluded for the same reason plus its own: nobody wants a
forum thread per lockfile bump.

Not fixed here, deliberately: making these actually review bot PRs would need
the org's review credentials copied into the Dependabot secret scope, which is a
wider grant than this is worth given the PRs in question are lockfile diffs.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* ci: gate the close-time Discord job too, and trim the comments

Both reviewers caught the same gap: merge_success_emoji runs on every `closed`
event with no exclusion, and the reusable workflow it calls exits 1 when it
cannot find a thread. Since open_thread no longer creates one for Dependabot,
the failure would have moved from open-time to merge-time rather than going
away. Gated to match.

The comments are cut from eight lines to two per file. AGENTS.md:205 asks for
constraints in <=4 lines, stated once, describing the code as it is — mine
narrated the drafting history and argued the change to a reviewer, both of which
belong in the PR description. Also drops "bot-authored", which overstated a
condition that only covers dependabot[bot].

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

.github/workflows/codex-pr-review.yml

@@ -40,11 +40,14 @@ jobs:
     # an author_association gate: the pull_request webhook payload reports private org
     # members as CONTRIBUTOR/NONE (only public members show as MEMBER), which silently
     # skips auto-review for every private member.
+    # Dependabot-triggered runs get a separate secret scope, so this job has no API
+    # key and cannot review. workflow_call stays open for an explicit request.
     if: |
       github.event_name == 'workflow_call' ||
       (
         github.event.pull_request.draft == false &&
-        github.event.pull_request.head.repo.fork == false
+        github.event.pull_request.head.repo.fork == false &&
+        github.event.pull_request.user.login != 'dependabot[bot]'
       )
     permissions:
       contents: read

.github/workflows/discord-notification.yml

@@ -13,7 +13,8 @@ on:
 
 jobs:
   notify_discord_when_pr_opened:
-    if: (github.event.pull_request.draft == false) && (github.event.action == 'opened' || github.event.action == 'ready_for_review')
+    # No thread is opened for Dependabot PRs, so nothing downstream may assume one.
+    if: (github.event.pull_request.draft == false) && (github.event.action == 'opened' || github.event.action == 'ready_for_review') && (github.event.pull_request.user.login != 'dependabot[bot]')
     uses: ./.github/workflows/shareable-discord-notification.yml
     with:
       PR_TITLE: ${{ github.event.pull_request.title }}
@@ -28,7 +29,8 @@ jobs:
       DISCORD_BOT_TOKEN: ${{ secrets.DISCORD_AI_BOT_TOKEN }}
 
   merge_success_emoji:
-    if: github.event.action == 'closed'
+    # Must match open_thread's exclusion: this reacts to a thread that was never created.
+    if: github.event.action == 'closed' && github.event.pull_request.user.login != 'dependabot[bot]'
     uses: ./.github/workflows/shareable-discord-notification.yml
     with:
       PR_STATUS: "merged"

.github/workflows/pi-pr-review.yml

@@ -38,11 +38,14 @@ jobs:
     # an author_association gate: the pull_request webhook payload reports private org
     # members as CONTRIBUTOR/NONE (only public members show as MEMBER), which silently
     # skips auto-review for every private member.
+    # Dependabot-triggered runs get a separate secret scope, so this job has no API
+    # key and cannot review. workflow_call stays open for an explicit request.
     if: |
       github.event_name == 'workflow_call' ||
       (
         github.event.pull_request.draft == false &&
-        github.event.pull_request.head.repo.fork == false
+        github.event.pull_request.head.repo.fork == false &&
+        github.event.pull_request.user.login != 'dependabot[bot]'
       )
     permissions:
       contents: read

.github/workflows/pr-ready-review.yml

@@ -37,11 +37,14 @@ jobs:
     # an author_association gate: the pull_request webhook payload reports private org
     # members as CONTRIBUTOR/NONE (only public members show as MEMBER), which silently
     # skips auto-review for every private member.
+    # Dependabot-triggered runs get a separate secret scope, so this job has no API
+    # key and cannot review. workflow_call stays open for an explicit request.
     if: |
       github.event_name == 'workflow_call' ||
       (
         (github.event.pull_request.draft == false || github.event.pull_request.ready_for_review == true) &&
-        github.event.pull_request.head.repo.fork == false
+        github.event.pull_request.head.repo.fork == false &&
+        github.event.pull_request.user.login != 'dependabot[bot]'
       )
     permissions:
       contents: read