fix: dispatch workers with /address-issue <id> only (#118)

[polymath-orchestrator]

Closes part of #118 (the ao-daemon half — intake + orchestrator dispatch surfaces). The sx-skills half (durable progress written to the ticket at each phase; AC #3) lives in the separate sx asset system and is tracked/synced there, not in this repo.

What changed

Two dispatch surfaces stopped emitting long, hand-shaped worker prompts and now emit exactly /address-issue <id>:

1. Daemon intake (trackerintake/observer.go) — BuildIssuePrompt dumped the full issue (title/url/labels/body) + an "implement the change… open a PR" footer. It now returns exactly /address-issue <id>. New intakeIssueRef reduces the canonical native id (owner/repo#N for GitHub) to the number the skill consumes, falling back to the trimmed native for a #-less id. The dead body-dump truncation machinery (intakePromptFooter, intakePromptTruncationNotice, maxIntakePromptLen, capIntakePrompt, truncateUTF8) is removed. The canonical id still rides in the session's IssueID env — only the prompt is trimmed.
2. Orchestrator system prompt (session_manager/manager.go) — orchestratorPrompt taught coordinators to ao spawn … --prompt "<clear worker task>". It now shows --prompt "/address-issue <issue-id>" and states plainly that every worker is dispatched with exactly /address-issue <issue-id> and nothing more, because the router is self-sufficient and durable context lives in the ticket.

Why

The router /address-issue already resolves the repo, reads the issue, claims, works, reviews, and (via the skills half) writes durable progress back to the ticket. Handing workers a long custom prompt is redundant and fragile — context in a spawn prompt dies with the session; context in the ticket survives and lets a resumed/replacement worker pick up from the id alone.

Acceptance criteria coverage (ao half)

• Daemon intake spawns a worker whose prompt is exactly /address-issue <id> — regression test TestBuildIssuePromptIsRouterInvocationOnly + TestPollSpawnsWorkerForEligibleIssue
• Orchestrator-spawned workers get /address-issue <id> only — TestSpawnOrchestrator_UsesCoordinatorPrompt asserts the new form and that <clear worker task> is gone
• No dispatch path emits the old issue-body-dump / "implement the change" footer — repo-wide grep in the PR sweep; dead code removed
• Regression coverage for the intake prompt (asserts /address-issue <id> form)
• sx skill durable-progress changes — out of repo, tracked/synced in sx
• Upstream PR — see note below

Vanilla rule / upstream

Both files are backend/daemon code under the hard vanilla rule. Changes are upstream-shaped (prompt content only, no structural fork). An upstream PR will be opened for the intake + orchestrator prompt changes; we carry the delta here.

session_manager/** is a sensitive path — autonomous merge parks this for a human reviewer by policy.

Testing

• go build ./..., go vet ./..., go test ./... — all green
• golangci-lint run (v2.12.2) on changed packages — 0 issues
• gofmt -l — clean

🤖 Generated with Claude Code

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[Copilot]

Pull request overview

This PR updates the backend daemon’s two worker-dispatch surfaces to emit only a /address-issue <id> router invocation (instead of long, hand-shaped prompts), aligning intake + orchestrator behavior with GH #118’s “router-only dispatch” contract.

Changes:

• Updated the orchestrator system prompt to instruct spawning workers with --prompt "/address-issue <issue-id>" and explicitly forbid custom task prompts.
• Simplified tracker intake worker prompts to "/address-issue <ref>" and removed the old issue body dump + truncation/footer machinery.
• Updated/added regression tests to pin the new router-only prompt behavior and ensure the old guidance/prompt content is gone.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
backend/internal/session_manager/manager.go	Orchestrator system prompt now teaches router-only worker dispatch.
backend/internal/session_manager/manager_test.go	Regression assertions for the updated orchestrator prompt + removal of old guidance.
backend/internal/observe/trackerintake/observer.go	Intake prompt generation now returns only /address-issue <id>; removed prompt-capping/body-dump logic.
backend/internal/observe/trackerintake/observer_test.go	Regression tests updated to assert exact router-only intake prompts.

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[polymath-orchestrator]

Final-review (independent, claude/fable — cross-family to the codex implementer): CLEAN. No medium+ findings.

• observer.go: BuildIssuePrompt → exactly /address-issue <id>; truncation/footer machinery removed; intakeIssueRef correctly reduces owner/repo#123→123 and passes non-GitHub refs through trimmed; test pins the exact prompt. Correct.
• manager.go: orchestrator prompt now mandates /address-issue <id>-only dispatch. It's the session_manager path (so it parks per policy) but the change is a prompt string — substantively low-risk, safe to merge.
  Verdict: merge-ready, parked for Nick (sensitive path). Gate the deploy behind Daemon restart must not SIGKILL running agents #123.