[unic-archon-dlc] Plan workflow — plan-checker loop, yaml-gen, and second PR gate

[orioltf]

Parent

docs/issues/unic-archon-dlc/PRD.md

What to build

Closes out the plan workflow with a validating loop that hardens the issue plan, a runtime YAML generator that turns the dependency tree into a build DAG, and the second human PR gate.

In scope:

• plan-checker loop node:
  • Max 3 iterations before escalation to a human gate.
  • Stall detection: if the issue count does not decrease between consecutive iterations, escalate immediately to the human gate rather than burning the remaining retries.
  • Validates four dimensions:
    • Consistency — no orphaned blocked_by references, all PRD acceptance criteria are covered by at least one issue.
    • Completeness — every mandatory field is present on every issue.
    • Decision coverage — every trackable decision in CONTEXT.md (and any decisions captured during specs) appears in at least one issue.
    • Nyquist compliance — every issue maps to a concrete test command (no lingering test_command_planned: true unless explicitly accepted at the gate).
• yaml-gen bash node: reads issues.json, builds the dependency DAG, detects parallel groups (issues with no shared blocked_by), and writes .archon/workflows/build-<slug>.yaml. Both code-red and code-green for independent issues are emitted as parallel-capable nodes. Linear chains produce serial nodes; circular dependencies are detected, reported, and abort the generation. Output YAML must be valid Archon syntax.
• Dependency tree builder + YAML generator module: pure data transformation, separately unit-tested. Test cases: linear chain → serial; independents → parallel; circular → reported; output round-trips through Archon's YAML parser.
• Second human PR gate (interactive: true): opens a PR containing issues.json, the generated build-<slug>.yaml, and the plan-checker report. Workflow pauses until approved. Rejected approvals return control to plan-checker for another validation pass (not a full re-decomposition).

Out of scope: executing the generated build YAML (slice 09).

Acceptance criteria

• plan-checker runs at most 3 iterations and escalates on stall (issue count stays equal between consecutive iterations).
• plan-checker reports failures across all four validation dimensions in a single structured report.
• yaml-gen produces a syntactically valid Archon YAML; circular dependencies abort with a clear error.
• Independent issues appear as parallel nodes; chained issues appear as serial nodes; both code-red and code-green carry parallel grouping when applicable.
• Dependency tree builder unit tests cover linear, parallel-fan, diamond, and circular cases.
• Second human PR gate stages issues.json + build-<slug>.yaml + plan-checker report in a PR and blocks until approved.

Blocked by

• [unic-archon-dlc] Plan workflow — to-issues, nyquist-map, and validation gate #107

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PRD: docs/issues/unic-archon-dlc/PRD.md
Migrated from: docs/issues/unic-archon-dlc/08-plan-checker-and-yaml-gen.md (source removed after migration)
Touched by PRs: #33