Rework single-agent workflows; add write-tests; remove comparative-plan

- claude-agent → standard-agent (complexity≥8, spec_adherence≥9 → Sonnet-class)
- smart-agent: complexity≥9 → Opus; documents MiniMax not in registry
- functional-agent: labels=[airouter], cost_efficiency≥9 → Qwen3.6
- write-tests: two-node DAG (write_tests → review_coverage), spec-driven
  test authoring with coverage gap report in JSON
- Remove comparative-plan (superseded by tdd-impl audit pattern)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

workflows/write-tests.yaml

@@ -0,0 +1,117 @@
+name: write-tests
+version: 1
+description: >
+  Two-node spec-driven test writing workflow. First node writes tests from the spec
+  (one test per requirement, edge cases, property tests where applicable). Second node
+  reviews coverage — checking every numbered requirement has a corresponding test and
+  flagging any gaps.
+
+  Output: test files committed to the agent-repo branch; coverage gap report in the
+  review node's output artifact.
+
+params:
+  required:
+    spec_file:
+      type: string
+      description: "Path to the spec file in the repo (e.g. spec/my-feature.md)"
+    project_id:
+      type: string
+      description: "Target project identifier"
+    repo_url:
+      type: string
+      description: "Git repo URL containing the spec"
+    agent_repo_url:
+      type: string
+      description: "Agent repo URL for branch-per-task output persistence"
+  optional:
+    task_description:
+      type: string
+      default: ""
+      description: "Additional context about what is being tested (supplements the spec)"
+    test_output_dir:
+      type: string
+      default: "tests/"
+      description: "Directory to write test files into (default: tests/)"
+    test_framework:
+      type: string
+      default: "pytest"
+      description: "Test framework to use (default: pytest)"
+    writer_harness:
+      type: string
+      default: "test-writing-opus-repo/v1"
+      description: "Harness for the test-writing node (default: test-writing-opus-repo/v1)"
+    reviewer_harness:
+      type: string
+      default: "planning/v1"
+      description: "Harness for the coverage review node (default: planning/v1)"
+
+nodes:
+  write_tests:
+    name: "Write tests from spec"
+    prompt: |
+      You are writing a test suite from a spec file. Tests are the contract — they will
+      be run against an agent's implementation. Write them now, before the implementation exists.
+
+      ## Spec file
+      Read the spec at `{{ spec_file }}` in the cloned repo at `/workspace/project/`.
+
+      {% if task_description %}
+      ## Additional context
+      {{ task_description }}
+      {% endif %}
+
+      ## Instructions
+      1. Read the spec carefully. Identify every numbered requirement (e.g. MY-1, MY-2...).
+      2. For each requirement, write at least one test function named `test_<req_id>_<short_description>`.
+      3. Cover edge cases explicitly — empty inputs, boundary values, error paths.
+      4. Add property-based tests (Hypothesis) where the requirement involves ranges or invariants.
+      5. Write tests to `{{ test_output_dir }}` — one file per logical group (mirrors spec sections).
+      6. Use `{{ test_framework }}` conventions. Tests should fail immediately (no implementation exists).
+      7. Do NOT write any implementation code. Only test files.
+
+      After writing all tests, write a coverage summary to `/workspace/project/output.md`:
+      - List every requirement ID from the spec
+      - For each: which test function(s) cover it
+      - Note any requirements you could not write a test for (and why)
+    harness: "{{ writer_harness }}"
+    requirements:
+      min_scores:
+        spec_adherence: 9
+        test_pass_rate: 8
+
+  review_coverage:
+    name: "Review test coverage"
+    depends_on: [write_tests]
+    prompt: |
+      You are reviewing the coverage of a freshly written test suite against its spec.
+
+      ## Spec file
+      Read the spec at `{{ spec_file }}` in the cloned repo at `/workspace/project/`.
+
+      ## Test summary written by the previous agent
+      <<ARTIFACT:write_tests:output>>
+
+      ## Instructions
+      1. Read the spec and extract every numbered requirement.
+      2. Cross-reference each requirement against the test summary above.
+      3. For each requirement, determine: fully covered / partially covered / not covered.
+      4. Flag any test functions that appear to test behaviour NOT in the spec (over-specification).
+
+      Write your review to `/workspace/project/output.md` as:
+
+      ```json
+      {
+        "covered": ["REQ-1", "REQ-2"],
+        "partial": [{"id": "REQ-3", "reason": "happy path only, error case missing"}],
+        "missing": ["REQ-4", "REQ-5"],
+        "over_specified": ["test_something_not_in_spec"],
+        "summary": "one paragraph"
+      }
+      ```
+
+      Then list specific, actionable improvements for any partial or missing coverage.
+    harness: "{{ reviewer_harness }}"
+    requirements:
+      min_scores:
+        complexity: 8
+        spec_adherence: 9