fix: harden worker prompt against context compression

[jflowers]

Summary

Hardens worker.md agent prompt against LLM context compression by restructuring critical behavioral constraints. Fixes #49.

The worker's file reservation enforcement, progress reporting requirements, and learning storage constraints were in a separate "Constraints" section vulnerable to being summarized away by context compressors. This restructuring integrates each constraint inline with the checklist step it governs, making them atomic units that compressors must keep or drop together.

Key changes:

• Constraints co-located with their checklist steps using MUST/NEVER language
• Reservation failure recovery path added (STOP + comms_send to coordinator)
• Separate ## Constraints section eliminated
• File reduced from 27 to 20 lines

How to Test

# Run the content-verification test
go test ./internal/agentkit/ -run TestWorkerPrompt_HardenedStructure -v

# Run the full suite
make check

Verify structurally:

• worker.md has no ## Constraints heading
• Step 3 (comms_reserve) includes "NEVER edit unreserved files" and reservation failure recovery
• Steps 5 and 6 use "MUST" language for progress reporting and learning storage
• File is 20 lines (under 35-line target from design decision D4)

How to Demo

cat internal/agentkit/content/agents/worker.md

Compare the before (separate Constraints section with flat bullets) to the after (all constraints inline with numbered steps). Each step now reads as "do X — MUST/NEVER Y" rather than having the constraint in a disconnected section.

Key Files Changed

File	Change
internal/agentkit/content/agents/worker.md	Hardened prompt: constraints inline, MUST/NEVER language, reservation failure recovery, Constraints section removed (27→20 lines)
internal/agentkit/agentkit_test.go	New TestWorkerPrompt_HardenedStructure — structural verification test for the hardened prompt
openspec/changes/harden-worker-prompt/	OpenSpec change artifacts: proposal, design, delta spec, tasks

This PR was generated by /uf.finale (AI-assisted).

[sonupreetam]

Review Council

Ran the review council (6 Divisor agents). Well-executed — the inline constraint approach is the right architectural choice and the test is thorough. One brittleness concern below.

Merge note: This PR inserts a test at line 152 of agentkit_test.go, same as #54 and #58. Suggest merging after #54, then rebasing.

[sonupreetam]

[MEDIUM] Single-line co-location assertion is brittle

This asserts that the line containing comms_reserve also contains comms_send. It works because step 3 is currently a single ~150-char line, but if someone reformats to use sub-bullets (like other PRs do), the test breaks even though the constraint is still co-located with the step.

Consider searching within a window of lines around comms_reserve rather than requiring everything on one line. For example, find the step and check the next 2-3 lines as well.