automaton/tasks/complete/fix-harness-command-template/IMPLEMENTATION.md

Implementation: fix-harness-command-template

Summary

Fixed the broken default harness.command in scripts/loop-runner.py. The old default ["opencode", "run", "--prompt-file", "{prompt}", "--cwd", "{cwd}"] used flags that do not exist in opencode run (--prompt-file, --cwd). The new default is ["opencode", "run", "--dir", "{cwd}", "{prompt_content}"] and introduces a new {prompt_content} substitution token that carries the resolved prompt's text as a single argv element. Added an explicit "Harness agnosticism" section to the SPEC confirming the contract is preserved (token substitution only; runner core has zero harness awareness; D8 intact).

Files changed

File	Change
scripts/loop-runner.py (lines 315-330)	Replaced default harness.command with --dir {cwd} {prompt_content}; added {prompt_content} token derived from reading the resolved prompt file
design/loops/technical.md §8	Updated default command in §8 and §9 to the new shape; documented {prompt_content} token; added Pi Dev / aider / generic examples
templates/loops/self-improvement/loop.json	Updated harness.command to new default
tests/test_loop_runner.py	_make_loop helper now writes loop-local prompt stubs (with role-marker content) so default-command tests' substring matchers still work; removed obsolete --prompt-file stub rules; updated the no-harness-invocation assertion to match opencode substring
tests/test_blast_radius.py	Same _make_loop helper change (with framework-prompt guard); no other test changes needed
tests/test_goal_mode.py	Same _make_loop helper change; three custom-{prompt}-command test matcher substrings updated from test-impl/test-verify/test-orch to implement-prompt/verify-prompt/orchestrate-prompt (those tests' matchers identify roles by the resolved temp-file path)
tests/test_loop_templates.py	Same _make_loop helper change (with framework-prompt guard); TestTickPromptSubstitution.test_tick_substitutes_prompt_tokens now uses a custom harness.command with {prompt} so its --prompt-file path extractor still works
tests/test_harness_command.py (NEW)	7 new tests for _invoke_harness covering: default uses --dir not --cwd/--prompt-file; default passes prompt content; prompt content preserves special chars (quotes, dollar signs, single quotes); {prompt} token still available for custom commands; {cwd} token still works in custom commands; empty command falls back to new default; Pi Dev-shaped command substitution works correctly (proves harness-agnostic token substitution)

Key decisions applied

• D-H1 {prompt_content} is a single argv element under subprocess.run list mode; no shell expansion, no quoting. Safe for any prompt text including special characters.
• D-H2 {prompt} (file path) retained for backwards compat and file-attachment harnesses.
• D-H3 Default does not hardcode --model; inherits from opencode config.
• D-H4 No per-role harness.command override in this task; one command for all roles, as in v1. Per-role model selection requires the per-role override feature (future task).
• The framework's harness-agnostic contract is preserved and extended: {prompt_content} makes the framework MORE harness-agnostic (covering harnesses that want a message arg, not a file path).

Verification

• python3 -m py_compile scripts/loop-runner.py ✓
• python3 -m pytest tests/test_harness_command.py -v 7 passed
• python3 -m pytest tests/test_loop_runner.py -v 18 passed
• python3 -m pytest tests/ -q 440 passed (baseline was 433; +7 new harness command tests)
• No live harness invocation; all subprocess calls mocked via fixtures.

Manual smoke (recommended before closing)

When opencode is on PATH (it is on this machine):

opencode run --dir /tmp --model local-mlx/AEON-7/Qwen3.6-27B-AEON-ULtimate-Uncensored-Multimodal-MLX-FP4 "echo hello"

should produce stdout and exit non-interactively. This confirms the new default shape actually invokes.