Session Analyzer

Session Analyzer

Produce a deterministic-first session report for debugging and teaching agentic coding with Claude MPM. The report reconstructs an entire session's timeline — every PM turn, subagent call, skill use, MCP call, the model behind each call, tokens in/out (plus cache), and a TOTAL estimated cost at public rack rates — directly from Claude Code's JSONL transcripts.

The core data is generated with zero LLM inference. Inference is an optional, opt-in polish step that only rewrites human-readable prose; the machine-readable data is never touched by a model.

When to use this skill

• Post-session debugging — understand what the PM actually did: which subagents ran, what they reported back, where time and tokens went, which MCP calls were made and how they responded.
• Teaching effective MPM usage — turn a real session into a readable, annotated timeline that shows good (and bad) delegation, skill use, and cost patterns.
• Cost analysis — see per-model and per-call token/cost breakdowns and a grand-total estimate at rack rates, split into PM vs. subagent cost.

The hybrid workflow

The workflow has three stages. Stages 1 and 3 are fully deterministic. Stage 2 is the only place inference is allowed, and it is entirely optional.

1. Extract (deterministic, no inference)

Run the offline reporter to parse the JSONL transcripts and emit the canonical Markdown report. This stage alone produces a complete, valid, usable report — token, cost, model, agent, skill, and MCP data, all with zero LLM inference.

# Most-recent session for the current project directory
claude-mpm session-report

# A specific session
claude-mpm session-report --session <UUID>

# Custom output path (use - for stdout)
claude-mpm session-report --session <UUID> --output /tmp/report.md

# A different project directory
claude-mpm session-report --project /path/to/project

Equivalent module form: uv run python -m claude_mpm.cli session-report ...

Flags:

• --session <id> — session UUID; defaults to the most recent session for the project.
• --project <path> — project directory whose transcripts to read; defaults to the current directory.
• -o, --output <file.md> — output path; - writes to stdout.

Default output path: docs/reporting/session-tracker/{session_id}.md

The generated file has two parts: a YAML frontmatter block (session metadata and cost totals) and a ## Timeline section with one ####-headed entry per event. Each entry carries a machine-readable <!-- meta: ... --> comment that holds the canonical per-call data (model, tokens, cost, type, attribution).

2. Optional narrative polish (opt-in inference)

This is the only non-deterministic stage, and it is optional — skipping it yields a fully valid report.

If you want a more teachable, readable report, you may edit the Markdown in place to rewrite each entry's prose:

• the #### HH:MM · {actor} · {title} heading text (the {title}),
• the entry's {detail} body prose,
• the **Outcome:** line.

Hard constraints — do not break these:

• Never alter the <!-- meta: ... --> comment on any entry. It is the canonical machine data the JSX renderer and downstream tooling read.
• Never alter the frontmatter totals (model_breakdown, grand_total_cost_usd, pm_cost_usd, subagent_cost_usd, autonomy, stat_cards, has_pricing_fallback, etc.).
• Only rephrase human-facing prose. Do not invent facts not present in the transcript.

3. Render (deterministic)

Convert the canonical Markdown into a standalone React/JSX timeline:

python scripts/session_timeline_to_jsx.py docs/reporting/session-tracker/<session_id>.md \
  -o docs/reporting/session-tracker/<session_id>.jsx

The script is bundled at scripts/session_timeline_to_jsx.py relative to this skill directory. An identical copy also lives at scripts/session_timeline_to_jsx.py in the repo root (used by the CLI render path and the test suite — do not delete the root copy).

The renderer reads the frontmatter + events structure parsed from the report and produces an interactive timeline dashboard. Because it consumes the <!-- meta: ... --> data, it works on both raw (stage 1) and polished (stage 2) reports identically — the polish only changes the prose it displays.

What each captured data point means

• Timeline entry — one event: a user prompt, a PM turn, an Agent call, a Skill call, an MCP call, or an outcome. Headed #### HH:MM · {actor} · {title}.
• actor — bob (the human), mpm (the PM agent), or a subagent attribution name (e.g. Python Engineer).
• Subagents called + their responses — Agent calls render as Agent → **agent-name** (model) — _short response to the PM_, capturing what each subagent reported back.
• Skills used — Skill → **skill-name** — _result_.
• MCP calls + responses — memory / search / review MCP invocations and their responses, tagged mcp.
• model — the model that served each call (e.g. claude-opus-4-8, claude-haiku-3), recorded per entry in the meta comment.
• Tokens — per call: in (non-cached input), out (output), cache_read, cache_write. Aggregated per model in model_breakdown.
• Cost — per-call cost_usd and a frontmatter grand total, split into pm_cost_usd and subagent_cost_usd.
• autonomy — {bob_pct, mpm_pct, basis}, a turn-count split of how much of the session was human- vs. PM-driven.
• stat_cards — six summary cards for dashboard rendering.

Caveats

Rack-rate cost estimates

All costs are estimates computed at Anthropic's public list prices (rack rates), not your actual billed amount. Rates used (USD per 1,000,000 tokens):

Unknown model strings fall back to sonnet rates, and the report sets has_pricing_fallback: true in the frontmatter so a fallback-affected total is visible and flagged. Treat such totals as approximate.

Subagent ↔ PM correlation

The parser links a PM Agent call to a subagent's JSONL transcript by matching timestamps within a ±2-second tolerance window (typical skew ~300 ms).

Under parallel delegation — multiple Agent calls fired nearly simultaneously — two PM calls can fall within the window of the same subagent file. The parser assigns the nearest match and sets ambiguous: true on the event. When you see an ambiguous entry, resolve it manually by inspecting the raw subagent transcripts in ~/.claude/projects/{encoded_cwd}/{session_id}/subagents/.

Reference

• references/schema.md — full canonical Markdown schema, frontmatter key reference, pricing table, and correlation details (bundled copy).
• scripts/session_timeline_to_jsx.py — the deterministic Markdown → JSX renderer (bundled copy; repo-root copy also used by CLI and tests).

Remember

• Stage 1 is a complete report on its own — run it and you already have every cost/model/agent/skill/MCP fact, with zero inference.
• Inference is opt-in and prose-only — never touch <!-- meta: ... --> or the frontmatter totals.
• Costs are rack-rate estimates — watch for has_pricing_fallback: true.
• Parallel delegation is ambiguous — verify ambiguous: true entries against the raw subagent transcripts.