feat(review-pr): emit and validate GitHub suggestion blocks

[Sayt-0]

Summary

Adds GitHub one-click suggestion blocks to PR reviews, plus a validator that sanitizes them before posting. GitHub rejects an entire review (HTTP 422) if any one inline suggestion anchors to an invalid line, so the validator strips malformed suggestions while keeping the prose finding, so one bad suggestion cannot lose the whole review.

What changed

Area	Change
Emission	The agent embeds a suggestion fenced block for findings with an exact fix on contiguous changed lines (review-pr/agents/pr-review.yaml, refs/posting-format.md)
Validation	New src/validate-suggestions module parses addressable right-side diff lines and strips suggestions GitHub would reject
Build and wiring	tsup entry plus action.yml staging; the validator runs before the gh api post; agent diff fallbacks redirect into pr.diff

Robustness (covered by unit tests)

Case	Handling
Path with a space (git trailing tab in the +++ header)	tab stripped so the key matches comment.path; suggestion kept
Non-ASCII path (git C-quoting)	header decoded back to UTF-8; suggestion kept
Closing fence shorter than the opener	closer must be at least as long; longer blocks are not truncated
Second opener before any closer	first block treated as unclosed and stripped, not merged
Comment with no integer line anchor	fails closed (stripped) instead of 422-ing the review
Prefetch failure	agent diff fallbacks write pr.diff so the validator reads the same diff

Validation

Check	Result
Unit tests	649 passed (35 in validate-suggestions)
Build (tsup)	pass
biome ci, tsc --noEmit	pass
actionlint	pass

Each robustness case was additionally reproduced against the implementation and confirmed handled via an independent adversarial verification pass.

[docker-agent]

Assessment: 🟡 NEEDS ATTENTION

[docker-agent]

[medium] findSuggestionBlocks stops scanning after the first unclosed block, silently dropping any closed suggestion blocks that follow it

When the body contains a closed suggestion block followed by an unclosed one (e.g. [closed][unclosed][…remaining…]), the outer loop breaks at line 261 as soon as the unclosed block is detected and sets end: lines.length - 1. This causes stripBlocks to treat everything from the unclosed opener to the end of the body as part of the unclosed block — including the content of any legitimate, properly-closed suggestion blocks that happen to come after it.

Trigger: a comment body shaped like:

```suggestion
const a = 1;

Some prose.

Suggested change

	break; // unclosed fence swallows the remainder; nothing left to scan
	const b = 2;
	← no closing fence here

The first block is valid and closed; the second is unclosed. findSuggestionBlocks records block 1 as {start:0, end:2, closed:true} and, when the inner loop finds no closer for block 2, pushes {start:4, end:N-1, closed:false} and breaks. The caller never sees block 1 as separate from block 2's range, so stripBlocks strips block 1's content as part of the unclosed range.

Impact: a valid, well-formed suggestion block after an unclosed one is silently dropped from the posted comment. The author's one-click suggestion is lost without any warning in result.issues.

Suggestion: instead of breaking out of the outer loop entirely, record the unclosed block and continue scanning from i + 1 (or from the index of the second opener when the inner loop broke on it). If "swallow to end of document" semantics are intentional, add a test for [closed][unclosed][closed] to document and assert that behaviour explicitly.

[derekmisler]

nice work overall. the validation logic is solid and the test coverage is thorough. one non-blocking thing to consider: the node /tmp/validate-suggestions.js call in posting-format.md has no guard for when the file is absent (the staging step only emits a warning and skips the copy). if dist/validate-suggestions.js is ever missing, the node call exits non-zero and could abort the shell before the gh api post runs. an easy fix: [ -f /tmp/validate-suggestions.js ] && node /tmp/validate-suggestions.js /tmp/review_comments.json pr.diff || true. ci is green, approving!