fix(ci): a fence opened inside a blockquote must close with the quote

[serina-mcfall]

Summary

_strip_fences in launchpad/scripts/pr_body_check.py kept no record of whether a fence opened inside a blockquote, so one opened with > and never explicitly closed stayed open past the quote's own end — silently consuming a Refs #<n> GitHub renders as ordinary prose, and blocking a compliant PR for appearing to have no issue reference.

Related issue

Closes #145

Issue type

Bug

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Agent provenance

Field	Value
Harness / provider	Claude Code
Model	claude-sonnet-5
Session reference	N/A - harness does not expose a run id/URL
Initiating human	@serina-mcfall

Objective

Make _strip_fences close a fence when the blockquote that contains it ends, so prose after the quote is no longer swallowed as leftover fence content.

Impacted components

• launchpad/scripts/pr_body_check.py (_strip_fences)
• launchpad/scripts/test_pr_body_check.py

Approach and rejected alternatives

Track whether the currently-open fence started inside a quote (fence_in_quote). On each subsequent line, if that flag is set and the raw line no longer carries a blockquote marker, force-close the fence before evaluating the line — so it falls through to ordinary prose handling instead of being swallowed.

Rejected: tracking full blockquote depth (nesting level) rather than a simple in-quote boolean. The issue's own converse case ("a quoted ``` closing an unquoted fence") is explicitly out of scope, and #145 only needs to know "did this fence open inside any quote, and has that quote now ended" — a boolean is sufficient and simpler to reason about than tracking depth for a case not being fixed here.

Verification

Command run:

python3 -m unittest test_pr_body_check

Raw output:

...............................................
----------------------------------------------------------------------
Ran 47 tests in 0.004s

OK

Confirmed the two new core tests fail against the pre-fix code with the exact symptom the issue describes:

FAIL: test_blockquoted_unterminated_fence_closes_on_a_bare_top_level_blank_line_too
FAIL: test_blockquoted_unterminated_fence_does_not_consume_prose_after_the_quote_ends
AssertionError: 'Refs #116' not found in '### Issue type\nTask\n\n'
FAILED (failures=2)

and that the regression guard (a fence that closes explicitly while still inside the quote must still close there) already held before the fix — confirming it guards against over-correction rather than duplicating the core fix's own assertion.

• Tests or checks were run and the raw output is pasted above
• The diff is confined to the scope of the linked issue
• No secrets, keys, tokens or hostnames were added to tracked files

Not verified

• Did not check this against a reference CommonMark parser — the fix follows CommonMark's stated lazy-continuation rule for block quotes, but wasn't cross-checked against commonmark.js or similar.
• The issue's own "converse leak" (a quoted ``` closing an unquoted fence) is explicitly out of scope per the issue text and is not addressed here.
• Did not test interaction with nested quotes (a quote inside a quote, each potentially containing a fence) — the issue's repro and scope are single-level.

Security implications

None. This only affects which lines of a PR body are treated as prose vs. code for the purpose of finding an issue-closing reference; it has no effect on repository content, secrets, or access.

Escalations

None — the fix follows directly from CommonMark's documented lazy-continuation rule, and the issue's own scope notes (bare > in-scope, quoted-fence-closing-unquoted-fence out-of-scope) left no ambiguity to resolve.