chore(stlc): run Promote SDKs on a daily schedule

Promote is a git-only fast-forward reconciliation between staging and
production main, not a release itself (release-please owns the actual
version bump/publish gate). Running it only on manual dispatch let
unpromoted staging content sit indefinitely, so an unrelated direct
push to production main (a docs PR) forked the trunks and blocked
back-sync until a maintainer manually reconciled it. A daily run keeps
that window small; workflow_dispatch remains for an eager promote.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FdU1YEnz7LjqjCiTP8cp6K

Author: tode-rl

.github/workflows/stlc-promote.yml

@@ -2,9 +2,15 @@ name: Promote SDKs
 
 # Promote staging to production by fast-forwarding production main up to staging,
 # preserving SHAs so the trunks stay identical and linear (nothing to heal on the
-# next stlc build). Manual dispatch by design: a maintainer promotes the accumulated
-# batch to cut a release; release-please then opens its version PR on production.
+# next stlc build). This is a git-only reconciliation, not a release: release-please
+# owns the actual version bump/publish gate on production. Runs daily so unpromoted
+# staging content can't sit long enough to fork against an independent production
+# push; workflow_dispatch remains for an eager promote. The fast-forward-only guard
+# below makes every run a safe no-op when there's nothing to promote.
 on:
+  schedule:
+    # 8am PT (15:00 UTC); shifts to 7am during PST since GitHub cron doesn't track DST.
+    - cron: '0 15 * * *'
   workflow_dispatch: {}
 
 permissions:
@@ -18,6 +24,9 @@ jobs:
     # Optional gate: add required reviewers to this environment to approve each
     # promote. With none it only scopes secrets and adds no gate. Remove if unused.
     environment: production
+    concurrency:
+      group: stlc-promote
+      cancel-in-progress: true
     env:
       PRODUCTION_REPO: runloopai/api-client-python
       GH_TOKEN: ${{ secrets.PRODUCTION_REPO_TOKEN }}