Agent memory (do not close)

[lsfera]

Durable cross-run memory for this repo's agent runs (ADR-0022). Do not close — comments here are read by future runs. Safe to edit or delete individual comments.

[lsfera]

Category: repo-convention

context-compressor.ts reads process.env.HEADROOM_MODE at call time (not at module load) so tests can set the env var after import. Any future env-driven feature flags in .sandcastle/ should follow the same pattern.