0.4.0

Changed

• The unit of capture is an artefact activation, not a skill invocation (ADR-009). The span
  std.skill.invocation is renamed to std.artefact.activation, discriminated by
  std.artefact.kind ∈ skill, subagent, compaction, turn. This is a wire-level rename and
  anyone querying Tempo or Prometheus for the old name must update; the shipped dashboards and
  deploy/smoke.sh already have. There is deliberately no dual-emission period — two spans would have
  doubled every traces_span_metrics_calls_total series and both dashboards. Compatibility lives one
  layer down: load_traces still writes skill_invocation from kind skill, so scorecard.sql,
  every existing query and every row recorded before the rename keep working unchanged, and spans
  still in Tempo under the old name keep loading. (#63)

Added

• Sub-agent, compaction and turn capture. A real session of this project's own spent $366, spawned
  42 sub-agents and compacted twice, and recorded one skill row and session totals — the numbers being
  collected could not answer "where did it go". New hooks SubagentStart, SubagentStop and
  PostCompact; where a hook has never fired the value is read from the session directory instead and
  flagged std.artefact.source=transcript, so an inference is never mistaken for an observation.
• The session's real cost. session_cost.cost_usd has been NULL for every row since the schema was
  written, because nothing read the harness's own cost-state entry. It and the harness's API and tool
  wall-clock totals are now loaded.
• Per-hook latency on each turn, as std.turn.hook.<basename>.ms. The basename only — the payload
  carries an absolute path, which is filesystem layout rather than data.
• warehouse/efficiency/: five versioned queries answering the named efficiency questions, and a
  session-efficiency brief in agents/skill-scorecard-analyst that runs them rather than writing its
  own. Efficiency is answerable for a single session at any volume; the primary effectiveness metric
  and its 30-merged-PRs-per-arm floor are unchanged.
• Scheduled loaders. mise run load, mise run load-watch, and an opt-in loader compose
  profile. Tempo held four days of spans the warehouse had never seen because load_traces.py is run
  by hand. Every run writes a loader_run row, including failures, and a dashboard panel shows how
  stale everything else on the page is.
• stdtel-doctor reports which of the new hook events have actually fired on this machine. Their
  payload shapes are transcribed from documentation, not captured, because hook configuration is read
  at session start and a session cannot observe a hook it just registered.

Fixed

• Dependabot branches minted phantom tickets (upload-artifact-7 → ARTIFACT-7), on spans as well
  as in the ticket table, putting work no developer did into the without-skill cohort. Both the
  capture and delivery parsers now anchor a ticket key to the start of a branch segment, bot-authored
  PRs are skipped, and a test pins the two parsers together because ADR-002 joins them on equality.
  (#62)
• span_id() silently mangled hex ids. A 16-character hex span id from Tempo's search API is also
  valid base64, so it was decoded into 12 bytes of a different id without raising. It now decodes only
  when the result is the length an id actually is.

Known issue

• A sub-agent span stamped more than roughly an hour in the past never becomes searchable in Tempo and
  never reaches the warehouse, with no error anywhere. The exposure is background sub-agents, which are
  the expensive ones. (#67)