feat(dispatch): port prioritize to harness CEL trigger

[ifireball]

What is missing

prioritize routing logic lives in bash in reusable-dispatch.yml. It is not expressed as a CEL trigger: on the harness file, so routing cannot be customized without editing shared dispatch bash.

What should happen

One vertical PR ports prioritize only:

Harness

• Add trigger: CEL expressing today's bash routing for: /fs-prioritize, schedule
• CEL lint/type-check in the same PR

Gating

• Decide prioritize-specific gates (may differ from GCD): what moves into fullsend dispatch, what stays in workflow, whether new ADR or harness format extension is needed
• Decide whether roles: config check still applies for prioritize in a custom-agents world

Workflow

• harness-dispatch handles prioritize when CEL matches
• Bash route still runs in parallel for shadow/diff until cutover epic child
• Do not remove bash routing for prioritize in this PR

Tests (same PR)

• Extend behaviour scenarios from test(behaviour): add prioritize dispatch trigger scenarios (bash routing) #2895 to cover harness-dispatch path
• Unit parity golden: normative fixtures for prioritize events match bash routing

Prerequisites

• feat(dispatch): add harness-dispatch job with ADR 54 auth, kill switch, and custom-agent behaviour test #2889 (harness-dispatch + custom agent)
• test(behaviour): add prioritize dispatch trigger scenarios (bash routing) #2895 (prioritize bash trigger behaviour baseline)

Merge criterion

prioritize behaviour scenarios green on harness-dispatch; shadow diff shows parity with bash for its trigger set.

Related

Part of epic #2888

[fullsend-ai-triage]

🤖 Finished Triage · ✅ Success · Started 8:34 AM UTC · Completed 8:36 AM UTC
Commit: 9f4f2b6 · View workflow run →

[fullsend-ai-triage]

Triage: blocked on prerequisites

This issue is well-specified and ready for implementation once its two prerequisites land:

1. feat(dispatch): add harness-dispatch job with ADR 54 auth, kill switch, and custom-agent behaviour test #2889 — harness-dispatch job with ADR 54 auth, kill switch, and custom-agent behaviour test. This delivers the fullsend dispatch command and harness-dispatch workflow job that this issue needs to wire prioritize into. Status: open.
2. test(behaviour): add prioritize dispatch trigger scenarios (bash routing) #2895 — Prioritize dispatch trigger behaviour scenarios (bash routing baseline). This establishes the normative behaviour fixtures that this issue extends to cover the harness-dispatch path. Status: open.

Both are part of the same epic (#2888). Once they merge, a developer can begin porting prioritize's trigger logic to CEL expressions and extending the behaviour scenarios.

The scope is clear: add a CEL trigger: expression to the prioritize harness, wire it through harness-dispatch, run shadow/diff alongside bash routing, and extend behaviour tests for parity. The gating decisions (whether roles: config check applies, whether a new ADR is needed) are called out as in-scope decisions for this PR.

Blocked by:

• feat(dispatch): add harness-dispatch job with ADR 54 auth, kill switch, and custom-agent behaviour test #2889
• test(behaviour): add prioritize dispatch trigger scenarios (bash routing) #2895