Fix multiple PRs opened for single autoloop program

[Copilot]

Autoloop creates a new PR with a hash-suffixed branch (e.g. autoloop/build-tsb-pandas-typescript-migration-480c452af2b58478) on every iteration instead of pushing to the existing PR. 20+ orphaned PRs accumulated for the same program.

Pre-step PR detection (autoloop.md)

The scheduling pre-step now queries the GitHub API for an existing open PR on the canonical branch before handing off to the agent:

pr_api_url = (
    f"https://api.github.com/repos/{repo}/pulls"
    f"?state=open&head={owner}:{head_branch}&per_page=5"
)

Outputs existing_pr (PR number or null) and head_branch (canonical name) in autoloop.json. Falls back to the state file's PR field if the API call fails.

Agent instructions (autoloop.md)

• Step 1, Step 5, Reading Programs docs, and Common Mistakes all updated to reference existing_pr as the primary signal for whether to use push-to-pull-request-branch vs create-pull-request
• The agent no longer needs to discover PRs itself — the pre-step provides the answer

Experiment log issue links (autoloop.md)

The experiment log issue body format now includes a prominent links table at the top showing Branch, Pull Request, Steering Issue, and State File — making each program's resources immediately discoverable from the long-running issue.

Stale branch filtering (sync-branches.md)

The sync workflow now skips branches matching -[0-9a-f]{16}$ (framework-generated hash suffixes), only syncing canonical autoloop/{name} branches. Prevents wasted merge work on dozens of orphaned branches.

Lock files

Recompiled via gh aw compile.

[mrjf]

@copilot Can we store the existing branch and name open PR link in the long-running issue for each program, linked prominently at the top? That way we know exactly where to find it. Also, make it CONVENTIONAL, with the program name as the branch name, so it's always obvious (I thnk we do that already).

[Copilot]

@copilot Can we store the existing branch and name open PR link in the long-running issue for each program, linked prominently at the top? That way we know exactly where to find it. Also, make it CONV...

Done in d3d7f15. The experiment log issue body format now has a prominent links table at the top showing Branch, PR, Steering Issue, and State File — matching what the steering issue and status comment already had.

The branch naming is already conventional: always autoloop/{program-name} with no suffixes. The head_branch field in autoloop.json (added in this PR) reinforces that by providing the canonical name from the pre-step.