* fix+test(#2828): total_phases uses roadmap count on flat unmilestoned roadmap
The read-path disk-scan cache fell back to phaseDirs.length (1) when milestoneBounded
was false, even though roadmapPhaseCount (6) was correct for a flat roadmap (no sibling
milestones to conflate). Use roadmapPhaseCount as the floor when > 0, matching the
write-path (cmdStateSync) which already did this. The milestoneBounded flag still flows
to milestoneUnbounded for the percent-skip (#1761 guard preserved). Regression test
asserts state-sync writes progress.total_phases:6 for a flat 6-phase roadmap + 1 phase dir.
* chore(#2828): changeset fragment
* test(#2828): add negative-space coverage (Math.max floor mutant + no-roadmap fallback) — review findings
The 6-phase test alone couldn't kill a Math.max-dropping mutant (1<6). Add: a
3-phase-dir/2-roadmap-phase case proving Math.max(dirs,count) floor; a no-roadmap
case proving phaseDirs.length fallback.
* fix(#2828): refine — distinguish flat unmilestoned from milestoned-unbounded (preserve #1761)
The first-pass fix (roadmapPhaseCount > 0 always) re-broke #1761: a milestoned-
unbounded roadmap (asserted milestone not among existing version headings) conflated
sibling milestones (8 = 4+4). Refine with a hasMilestoneSectioning discriminator:
^#{2,3}(?!Phase) detects non-Phase h2/h3 milestone section headings. A FLAT roadmap
(only ### Phase headings + a # title) has none → safe to use roadmapPhaseCount; a
SECTIONED-but-unbounded roadmap has them → fall back to phaseDirs.length (#1761).
Verified both cases locally (flat→6, sectioned-unbounded→1).
* test(#2828): remove two fragile negative-space tests (phase-dir scanner internals)
The Math.max-floor and no-roadmap tests made assumptions about the phase-dir scanner's
internals (which dirs count as 'realized') that didn't hold. The core regression test
(6-phase flat → total_phases:6) plus the existing #1761 conflation tests (which the
refined fix preserves) provide sufficient coverage.
* chore(#2828): backfill changeset PR number 2892
* fix(#2828): replace ReDoS-prone regex in regression test with line-by-line parse
CodeQL flagged the nested-quantifier regex (`(?:[ \t]+\w+:.+\r?\n?)*?`) in
tests/issue-2828-flat-roadmap-total-phases.test.cjs as a high-severity
catastrophic-backtracking risk. Rewrite the STATE.md progress.total_phases
extraction as a ReDoS-safe line-by-line block walk.
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Co-authored-by: Test <test@example.com>
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