Intent: reject malformed input without partial content

[noeltock]

Problem

Malformed intent nodes, list items and table cells could disappear or become empty content while reporting success. Closes #127.

Solution

Reject malformed values where the existing assembly walk consumes them. Errors identify the input path and expected shape; realize returns its existing failed report and low-level assemble rejects.

Behaviour	Read first	Proof
Invalid nodes, children, items and cells report their locations	src/intent/index.ts	Parameterized intent regressions
Valid wrappers, native tables and unused shorthand retain precedence	dev/test/intent.test.ts	Positive controls
Fail before media processing and preserve existing output	dev/test/intent.test.ts; dev/test/cli.test.ts	Resolver spy and CLI output sentinel

Diff

+100 / −19 across three files.

 assembleWithWp(nodes, intentPath)
- missing block name -> skip node
+ malformed node or children -> throw path-located error
 assembleNode
- consume unchecked list items / table cells
+ check consumed string values at their input paths
 realize catch -> invalid report, empty output

Testing & verification

Reviewed revision: de9f02a60a098e2404dfb6b94352569b004ba730 · Environment: Node 24.18.0, macOS arm64.

• npm run typecheck: passed.
• git diff --check: passed.
• npx vitest run dev/test/intent.test.ts dev/test/cli.test.ts: 69 passed.
• Full PR CI passed: https://github.com/humanmade/block-runner/actions/runs/37174717824 (Node 20/22/24, package consumers, WordPress proof and scope gate).

Not verified: destination-site rendering or manual editor acceptance. These are input-construction checks against the pinned headless runtime.

Risk / rollout

Malformed input now fails instead of returning partial content. The attribute envelope remains open; no preflight schema or coercion is introduced.

Detection: input-path regression tests and CLI sentinel checks. Rollback: revert this PR; doing so restores the previous partial-output behavior.