[guijacquemet]

Stage 1 notebook PR 16a: screen 4 Your masks and the Step 3 reuse of its IDs (design notebook-natural-design-2026-11-08.md §2 "Screen 4", owner answer 4). PR 16b (screen 5 Check and save, reopen, thumbnails on screen 2, retiring the global Image type card and labels toggle) is stacked on this one.

What the screen does

• Shown only when the folder check paired masks (or the draft already declares some), after the axis roles are confirmed (pictures are read only through them, as on Your channels).
• One question per mask type: separate objects, each with its own number (instances) or regions: inside or outside (binary). Nothing preselected (experiment-v1 §4.5).
• Mask ID = folder name when valid (Token rule, reserved list, object-set part in: draft_ids.id_problems("masks", …), the reader's own rules). Otherwise the box is empty and says why (nuclei-mask: E_ID_SYNTAX; cell: E_ID_RESERVED), and the user types one. Nothing is repaired.
• Made from (optional): one toggle per declared channel label, enabled once the question is answered; saved as source_channels.
• Evidence beside it: images with the mask (k of n), pixel type(s) from the mask headers, the number of different values in the representative image's mask plane (read with the mask step's masks.read_mask), and two pictures: the image channel (PR 13 channel_strip), and the mask reduced with the same step (preview.labels_thumbnail, never interpolated). Before an answer the mask is drawn alone in grey; after it, as declared (mask_overlay_png: outlines or tint). The mask is drawn on the channel tagged with its first made from label, else channel 1, and the caption says which.
• A declared mask whose files are gone is listed in orange with Remove (a declared mask without files is valid, §4.5).
• Every answer is saved at once in morphobricks.draft.json (DraftAnswers.masks); the card is a self-contained MasksCard reading and saving through the AnswerStore, like Notebook: your channels (labels first, then tag per unit) (Stage 1, PR 15) #233's cards (owner note).
• Step 3 Describe the masks shows a Mask ID column (not described yet for an unanswered type) and no longer says "name each mask".

Library

mask_answers.py (pure): with_mask, without_mask, proposed_mask_id, mask_ids, masks_unanswered, masks_without_files, dropped_channels, drawn_on. mask_evidence.py (io): mask_evidence, representative. preview.labels_thumbnail. draft_ids kind masks. mask_text.mask_type_rows(report, ids).

Tests

tests/test_notebook_masks_screen.py (9 headless widget tests), tests/test_mask_answers.py (20 library tests), one new test in tests/test_notebook_mask_step.py (IDs reused, no "name each mask"). All fail on origin/main (the modules and the column do not exist there).

Gate (python tools/check.py, .[dev,notebook,zarr], Python 3.13): ruff check and format clean, code rules clean (no baseline grown), 4802 passed, 4 skipped (the existing case-sensitive file system and file-mode skips), and 1 failure: the embedding API pin of the new public masks_step. Fixed in 459dd02 (pinned); tests/test_embedding_api.py then passed 36/36. CI on 459dd02: all 7 jobs green.

Screenshots (rendered in Chromium from real widget state, synthetic structured images) are in the PR 16b report: pr16-02-screen4-masks-unanswered.png and pr16-03-screen4-masks-answered.png.

https://claude.ai/code/session_01G3qp9AxjpGPw9xfWAUJNqc

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