Make an empty project-instructions-path actually disable the file

[theletterf]

Summary

project-instructions-path: "" is documented as the way to disable the project instructions file, but it didn't work: in sandbox testing the agent read .github/triage-instructions.md anyway.

With the input empty, the prompt rendered as "If `` is not empty, use the GitHub repository read tools to read that path" — a degenerate sentence the model skipped, after which it went and found the conventional file on its own. The run artifact shows an explicit get_file_contents on `.github/triage-instructions.md`, with the input confirmed empty in the activation log.

The empty case is now stated explicitly: do not read any instructions file, not even one at the default location, because the caller disabled it deliberately. Applied to issue-triage, issue-auto-triage, and issue-scope, which share the construction. Lock files recompiled.

No interface change. Callers that never set the input to "" see no difference.

Test plan

• gh aw compile clean on all three workflows
• New wording present in all three compiled lock files
• Sandbox: /triage with project-instructions-path: "" applies type + triaged only — no board metadata, and no get_file_contents on the instructions path in the agent artifact

🤖 Generated with Claude Code

[github-actions]

Approved: no actionable issues found.

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[theletterf]

Sandbox result for the unchecked test-plan item — partial.

With project-instructions-path: "" and .github/triage-instructions.md present in the repo:

• Reduce docs-review suggestion noise #117 → documentation, triaged — correct, no board metadata, file not read.
• Harden docs-review substitution suggestions #118 → documentation, triaged, priority:high, area:esql — the agent still called get_file_contents on .github/triage-instructions.md (confirmed in the run artifact) and applied the board-metadata table from it.

So the explicit wording helps but does not reliably stop haiku from reading the conventional path when the input is empty. I'm not going to iterate on prompt wording further; today's triage work showed that's a poor lever on this model tier.

The gap is narrow in practice: it only bites when a repository has the file and a caller passes "" to suppress it. A repository that wants no project instructions simply doesn't have the file — which is docs-content's situation — and that path is unaffected. Worth merging as a strict improvement, with the README caveat that "" is best-effort rather than a hard disable.