Evidence context can exhaust its own budget

Retrieval-method learning, observed 2026-09-07 while investigating passage delivery: adding a short source-quoted turn opening to every long-turn window can help preserve subject and qualifications, but repeating that opening in the returned evidence bundle consumes space needed for the answer's continuation. A bounded alternative is to retain the opening once per exact source turn/prefix and link later windows to that included chunk. Budget whole windows, flag omitted context, and preserve each window's own source identity. Test the actual delivered bundle—not candidate/message-ID hits. Also keep family deduplication separate from evidence collapse: one family result can need several passages. This supports separating diagnostic plumbing evidence from benchmark claims; context expansion changes the treatment and needs a matched-budget evaluation before claiming a ranking improvement. Provenance: implementation review and synthetic regression tests in e3-solutions/sesh commit 4482607 (https://github.com/e3-solutions/sesh/commit/4482607), tests/test_evidence_bundle.py; no source transcript or workload questions included.