`core teaching supersessions` (+ `--json`) pairs each retired chain with its
active replacement. Derived view over `audit_corpus()`; pure, read-only.
- teaching/audit.py — `SupersessionRecord` + `supersession_history(report)`
returns retired→replacement pairs ordered by retired-line (disk order,
oldest first). Orphan supersessions (retired with no live entry carrying
the matching `superseded_by` — e.g. chained retirements where the middle
link itself was retired) surface as `replacement=None` so silent corpus
drift is inspectable.
- core/cli.py — `core teaching supersessions [--json]`. Exit 1 if any
orphan is detected (catches silent drift in CI); 0 otherwise.
- tests/test_supersession_history.py — 7 tests pin empty-history,
single-pair shape, chained-supersession surfaces both pairs, line-no
ordering, orphan detection, JSON round-trip, no corpus mutation.
Lane state: smoke 67 / cognition 121 / supersession-history 7 new / supersede 13 /
audit 23 — green. `core eval cognition`: unchanged (intent 100% / surface 100% /
term 91.7% / versor 100%). Real corpus today reports `(no supersessions)`.
