id(web): saving a table cell with a hard break or a list panics in the markdown codec — ill-formed comrak AST

Summary

Saving a document whose table cell contains anything other than plain paragraph text can panic in the markdown codec: prosemirror_to_markdown builds an ill-formed comrak AST and format_commonmark panics instead of returning markdown (or an error).

Evidence (verified 2026-10-26 on main `786d2129`, standalone verbatim-codec probe)

Probe: hidden_files/probe-2026-10-26-1615/ (crate = current pkgs/id/src/web/markdown.rs copied verbatim + round-trip harness).

Case 1 — a hard_break inside a table cell (PM JSON: table → table_row → table_cell → paragraph → text line1, hard_break, text line2):

thread 'main' panicked at comrak-0.56.0/src/cm.rs:29:9:
The document to format is ill-formed: InvalidChildType {
  parent: <TableCell> [<Text("line1")>, <LineBreak>, <Text("line2")>],
  child: <LineBreak> }

Case 2 — a bullet_list inside a table cell: same panic, InvalidChildType { parent: <TableCell>, child: <List …> }.

Root cause

pkgs/id/src/web/markdown.rs:1090-1110 (json_to_ast, table-cell special case): paragraph children are unwrapped inline into the cell, and any non-paragraph child is also appended directly to the cell node via append_inline_child (:1106) — including block nodes (lists, code blocks, quotes). hard_break maps to NodeValue::LineBreak (:1074), which comrak's CommonMark renderer also rejects as a direct child of TableCell. comrak validates the tree in format_commonmark and panics on the ill-formed AST; the codec returns Result<_, ConversionError> everywhere else, so this input escapes the error channel entirely. In the server this is a panic on the save path for a document the editor can plausibly produce (Shift+Enter inside a cell; pasted/structured content with a list in a cell).

Related, already tracked separately: multi-paragraph cells fuse words (#1003) — that is the paragraph-unwrap path; this issue is the non-paragraph / LineBreak path that crashes outright.

Acceptance criteria

prosemirror_to_markdown never panics for any PM doc the schema can express in a table cell; ill-supported cell content degrades to a defined representation (e.g. hard break → space or literal text; block content → flattened inline text) or returns ConversionError.
Regression tests in pkgs/id/src/web/markdown.rs covering at least: hard_break in a cell, list in a cell, code_block in a cell — each asserting a non-panicking, content-preserving-as-possible output and a stable second save (fixpoint).
Existing markdown codec tests still pass.

Suggested direction

In the table-cell special case, sanitize children before appending: convert LineBreak to a space/text node inside cells, and flatten non-inline block children to their inline text (or reject with ConversionError::UnknownType-style error) instead of attaching them under TableCell.

CODE-179

🤖 Agent note · filed

Agent: new-issue-creator job
Session / ID: new-issue-creator cron run 2026-10-26 16:10 CDT
Found via: filed this run
Task: Verified with a standalone verbatim-codec probe on main 786d212 (logs hidden_files/probe-2026-10-26-1615/err.log + err2.log): PM table cells containing a hard_break or a bullet_list make prosemirror_to_markdown build an ill-formed comrak AST (LineBreak / List directly under TableCell, json_to_ast cell special case markdown.rs:1090-1110) and format_commonmark panics at comrak cm.rs:29 instead of returning markdown or an error. Enqueued as a triage packet to repo-health-code-pilot — the degradation choice for unsupported cell content needs a decision.
Expectation: triage decides the cell-content degradation rule; done when no PM cell content can panic the save path and regression tests cover hard_break/list/code_block cells.
Links: probe evidence in goal hidden_files (see issue body)

🤖 Agent note · parked

Agent: queue worker (repo-worker-code), lane A shift
Session / ID: queue task 1180
Found via: queue claim
Task: Parked awaiting CI on PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 (table-cell degradation fix for the save panic). Fix is implemented and probe-verified (pre-fix panic reproduced; post-fix all cases convert with fixpoints); CI was 7 pass / 20 pending / 0 fail at park time.
Expectation: resume = merge PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 when CI is green, verify id(web): saving a table cell with a hard break or a list panics in the markdown codec — ill-formed comrak AST #1017 auto-closes, complete the task.
Links: PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 · branch queue/1180-1017-table-cell-panic (f32a41e) · probe logs hidden_files/probe-2026-10-26-1627-t1180/

🤖 Agent note · picked up

Agent: queue worker (repo-worker-code), lane B shift
Session / ID: queue task 1180, run 2026-10-26T21:53Z (resumed from park)
Found via: queue claim (repo-health-code-pilot)
Task: Resume id(web): saving a table cell with a hard break or a list panics in the markdown codec — ill-formed comrak AST #1017 table-cell panic fix: PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 was parked awaiting CI (7 pass / 20 pending / 0 fail at park time).
Expectation: effort/xs — fresh check at pickup: all 28 PR checks PASS, head still f32a41e; merging per standing criteria, then verifying id(web): saving a table cell with a hard break or a list panics in the markdown codec — ill-formed comrak AST #1017 auto-closes and completing the task.
Links: PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 · branch queue/1180-1017-table-cell-panic

fix(id-web): degrade unsupported table-cell content instead of panick…

🤖 Agent note · done

Agent: queue worker (repo-worker-code), lane B shift
Session / ID: queue task 1180, run 2026-10-26T21:53Z
Found via: queue claim (repo-health-code-pilot)
Task: Table-cell hard_break/list panic on save — PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 degrades unsupported table-cell content instead of building an ill-formed comrak AST.
Expectation: met — on resume, all 28 PR checks passed; merged PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 (squash, merge commit 97cf446); this issue auto-closed by the merge.
Links: PR fix(id-web): degrade unsupported table-cell content instead of panicking on save (#1017) #1021 (merged)

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id(web): saving a table cell with a hard break or a list panics in the markdown codec — ill-formed comrak AST #1017

Summary

Evidence (verified 2026-10-26 on main `786d2129`, standalone verbatim-codec probe)

Root cause

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id(web): saving a table cell with a hard break or a list panics in the markdown codec — ill-formed comrak AST #1017

Description

Summary

Evidence (verified 2026-10-26 on main 786d2129, standalone verbatim-codec probe)

Root cause

Acceptance criteria

Suggested direction

Activity

developing-today commented on Oct 26, 2026

dezren39 commented on Oct 26, 2026

5 remaining items

dezren39 commented on Oct 26, 2026

dezren39 commented on Oct 26, 2026

dezren39 commented on Oct 26, 2026

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Evidence (verified 2026-10-26 on main `786d2129`, standalone verbatim-codec probe)