Module plan_status 

Algorithmic plan / task status densification for FTS and agent summaries.

Plans are ordinary Markdown. Rustbrain does not require a kanban product. On index, it extracts a compact status vocabulary so agents can query and pack status without reading whole roadmaps:

Canonical	Accepted surface forms
backlog	backlog, todo, open, pending, queued
in_progress	in_progress, in-progress, inprogress, wip, doing, active
qa	qa, review, in-review, testing, verification
done	done, complete, completed, finished, closed, shipped (task-level)
cancelled	cancelled, canceled, wontfix, dropped, obsolete
blocked	blocked, stuck, on_hold, paused, deferred, undone, reopen, reopened

Sources (first wins for overall status when explicit):

1. YAML frontmatter status: / state:
2. ## Status section body (first status token)
3. Section headings (## In Progress, ## Done, …)
4. Checkbox lines (- [ ], - [x], - [/], - [~])

Dense FTS tokens use stable prefixes (status:…, task:status:slug) so they survive stopword stripping and stay machine-readable.

Structs

PlanStatusDigest

Aggregated densification for a plan note body (+ optional frontmatter status).

PlanTask

One extracted checklist / task line.

Enums

PlanStatus

Canonical task / plan lifecycle status.

Functions

densify_plan

Build a digest from optional frontmatter status string + markdown body.

enrich_plan_index_fields

Enrich FTS body + summary for plan notes when status signal exists.