ADR 0212: Remove diagnostic timing log streams

• Status: Accepted
• Date: 2026-09-10
• Amends: ADR 0046 · D183
• Related: Logging and observability

Context

D137/D183 added per-tool, per-model, boot-phase, and updater timing output to help diagnose a slow run. The investigation is complete, and those records now create noise in local log directories during normal use.

Decision

1. Stop emitting sidecar [timing] lines, host tool timing lines, boot-phase timing records, updater timing records, and renderer bootstrap timing output.
2. Remove the dedicated timing log category and the PI_DESKTOP_TIMING suppression environment variable. The updater's functional timeout remains.
3. Keep key lifecycle, state-change, permission, tool, plugin, provider, persistence, updater, and error records. Keep structured audit fields and UI/protocol duration metadata that are consumed by product features or security forensics.
4. Do not delete or migrate timing files already present in a user's local data directory. They are historical records.

Consequences

• Normal launches, turns, retries, and tool calls produce fewer log records and no longer create dedicated timing files.
• Failures remain diagnosable through stable lifecycle records, error codes, tool/permission audit rows, and the visible transcript.
• Timing-specific troubleshooting scenarios and documentation are retired.
• Existing local timing files may remain until the user removes them.