* feat(session-start): rank injected instincts by project/stack relevance
Instinct selection at SessionStart ranked purely by confidence, so a
high-confidence instinct about an unrelated stack could take an injection
slot from a lower-confidence instinct that is actually relevant to the
current project.
Rank by confidence + location/stack relevance instead: project-scoped
instincts, and instincts whose domain/trigger matches the detected stack
(languages/frameworks via detectProjectType, plus terraform/dbt markers),
get a small additive boost. The confidence>=threshold floor and the
injection cap are unchanged, and ranking degrades to confidence-only when
nothing matches or when ECC_INSTINCT_RELEVANCE_RANKING is set to off.
The ranking helpers live in scripts/lib/instinct-relevance.js with unit
coverage in tests/lib/, plus an end-to-end ordering test in tests/hooks/.
Completes part (b) of #2371; part (a) (configurable count + threshold)
shipped in #2413.
Fixes#2371
* refactor(session-start): drop redundant confidence tiebreaker in instinct sort
Greptile flagged that the secondary `right.confidence` comparison in
summarizeActiveInstincts' sort was dead code when relevance ranking is
disabled and, when enabled, was reached only on a floating-point tie of the
combined score — where it skipped the intended scope-label tiebreaker.
Remove it: the primary combined-score comparison already reduces to
confidence-only ordering when relevance is off, so behavior there is
unchanged; a genuine combined-score tie now falls through to the documented
scope-first, then id, order.
* test: isolate instinct relevance environment
---------
Co-authored-by: haelyra <49814733+haelyra@users.noreply.github.com>
5987bd4dc6