Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.10 Home All releases olderv2.1.9 v2.1.11newer
Claude Code v2.1.10

Perfetto Performance Tracing [In Development]

What

Infrastructure for generating Perfetto-compatible trace files to analyze Claude Code performance.

Status

Feature-flagged, returns false. The PERFETTO_TRACING feature gate is disabled.

Details
  • Set CLAUDE_CODE_PERFETTO_TRACE=1 or provide a file path to enable (once feature flag is enabled)
  • Traces include API call timing, time-to-first-token (TTFT), token throughput metrics
  • Output in Chrome Trace Event format (trace-{sessionId}.json)
  • Tracks per-agent timing with parent-child relationships for nested agent calls
  • Includes metadata like input/output token counts, cache hit rates, and errors

Usage (when enabled):

CLAUDE_CODE_PERFETTO_TRACE=1 claude
# or
CLAUDE_CODE_PERFETTO_TRACE=/path/to/trace.json claude
Evidence

r_2() at line 356811 (initialization, checks process.env.CLAUDE_CODE_PERFETTO_TRACE but guarded by ix.PERFETTO_TRACING which returns !1)

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.10 →