WP-216 — cross-task training stories

Engineering log · Phase 19 — Codebase audit remediation

🔗 Depends on WP-215 · Needed by WP-217

⬅️ WP-215 · Roadmap · WP-217 ➡️

WP-216 — cross-task training stories

Finding. T3’s remaining training duplication repeats empty-image, branch-gradient and checkpoint-composition stories across task suites. Body comparison distinguishes data-only differences from task-specific actions and oracles: segmentation and keypoints share the empty-image oracle, all three tasks share the gradient oracle, and OBB and keypoints share the state-key oracle. Segmentation’s checkpoint-loading test also compares zero-gain training losses and is not the same story.

Change. Three parametrized tests retain each case’s model options, target generation, expected branches, log key and state-key exclusions. Existing target builders move into the shared training fixtures without changing their generated values; per-task suites import them by bare module name. Every original gradient assertion remains, including both head branches and the non-null pose flow. Assignment-order tests stay separate: segmentation compares mask losses exactly, OBB checks three zero and three positive terms, and keypoints compares against an RLE reference. OBB’s empty-image test retains its backward-connectivity assertions. No shipped code or changelog changes.

Verification.

• CPU. make gate green on this commit's tree. test_task_gradients_reach_every_branch, test_task_image_without_instances_gives_finite_zero_term and test_task_state_dict_keeps_detection_keys retain seven cases from seven original tests; the four distinct cases remain in their original suites.
• Body comparison. No pair is wholly identical. Gradient bodies differ by target builders, module options and branch names; the keypoint wrapper already installs its log recorder. Empty-image bodies for segmentation and keypoints differ by task options and expected log key. State-key bodies differ by stem substring and the flow prefix excluded for keypoints. The OBB empty-image actions and all three assignment-order oracles differ in behavior, so they are not merged.
• Case counts. Empty image: 3 → 3; assignment order: 3 → 3; branch gradients: 3 → 3; state keys: 2 → 2. The three original training files plus the shared story suite collect 109 → 105 items because four target-builder doctests move to tests/fixtures/training.py; those doctests remain collected by the full gate. Story cases remain 11 → 11. Segmentation has no standalone state-key case in the candidate files; its checkpoint-load and zero-gain-loss test remains unchanged.