v0.4.0

Added

• Continuity handoff doc — the agent's living, canonical working-doc (T2.29, ADR-18).
  A new handoff MCP tool (the fourth write surface) lets the agent maintain an evolving
  markdown document a fresh instance reads to resume fully: mission, current state,
  progress, exact next steps, key references, decisions + why, the user's own
  directives/corrections, system/process improvements discovered, and open questions.
  Stored at ~/.headroom/continuity/<session>.md, latest-wins, capped per section, session-
  guarded, pruned after 7 days. Re-injected at SessionStart(source=compact) as a pointer +
  digest (ADR-11 style — the doc lives on disk, so point, don't dump). Richer and more
  durable than the terse checkpoint. headroom handoff [--path] prints the current doc.

Changed

• Skill: context-pressure is a write-the-handoff signal, not a stop sign. Field report:
  agents were getting "tired"/cautious as compaction approached and slowing down or stopping.
  The "near the context ceiling" section is rewritten into a handoff ritual — keep a living
  handoff doc, refresh it when context runs low, then keep working at full speed; let the
  window burn to the floor because compaction is automatic and your doc + ground truth are
  re-injected right after it. The mid-turn ctx band update now says the same. (Wording
  eval-gated per ADR-9; validating in soak.)