# Ingest Traces > Use when a developer already has production LLM traces — a bucket of captures, provider log exports, or gateway capture files — and wants them visualized, turned into local redacted eval sets, or profiled for cost. "Visualize this trace", "ingest my traces", "turn these logs into an eval set", "where is my LLM spend going". - Skill: `understudylabs/ingest-traces` (Agent Skill, multi-file: 8 files) - Install (CLI): `npx skillmds@latest add understudylabs/ingest-traces` - Raw SKILL.md: https://api.skillmd.com/api/skills/understudylabs/ingest-traces/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: understudylabs (https://skillmd.com/u/understudylabs) - Updated: 2026-09-22 - Page: https://skillmd.com/skills/understudylabs/ingest-traces --- # Ingest Traces [`../capture-evidence/SKILL.md`](../capture-evidence/SKILL.md) assumes a local harness can be attached and run. Many workloads arrive the other way around: the traces already exist — in an object-store bucket, a provider log export, or an Understudy gateway capture export — and the job is to get them into local evidence artifacts without leaking anything. This worker does that transformation: local source → normalized captures → source-history DAG → machine-proposed benchmark → human judgment, all on the local machine. When the developer has only a hosted `trace_id`, acquire its private local files first with [`../export-trace/SKILL.md`](../export-trace/SKILL.md). This skill begins after capture files exist locally and does not recreate the hosted trace-to-request lookup. ## OSS filesystem boundary This public skill starts with files already present in `.understudy/captures/` or another explicitly supplied local directory. It never invokes a privileged administrative surface, changes tenant membership, or embeds a vendor-specific downloader. Acquisition is a separate producer; this skill owns processing. ## Safety Gates - **Raw bodies never leave the source files.** Manifests reference traces by path/key and carry counts, schemas, and hashes — never prompt text, completions, or tool payloads. Downstream tools fetch bodies from disk at runtime. - **No identifiers in artifacts.** Bucket names, org/account ids, and customer identifiers stay in local credentials/config; manifests use relative keys only. Every manifest records `privacy.local_only: true` and `privacy.upload_performed: false`, and is itself review-gated before any external reference. - Downloading from a customer-controlled bucket is a read of customer data — confirm the developer is authorized for that source before pulling, and keep the pulled files under `.understudy/` (gitignored). - Do not upload source files, prompts, traces, outputs, or datasets unless the developer explicitly approves that exact action in the current thread. ## Intake Identify the source shape first: - **Object-store bucket** (R2/S3-compatible): list keys with the developer's existing tooling (`aws s3`, `rclone`, `wrangler`); pull to a local staging dir. - **Provider log export**: JSONL/CSV of historical calls. - **Understudy frozen cohort**: select only workload-scoped, redacted capture metadata, review the summary, freeze the exact references, and materialize that auditable cohort locally: ```sh understudy evals create --project --workload \ --last 14d --name ``` The command shows how many eligible captures it found and asks before it freezes or downloads anything. Use `--yes` for non-interactive automation. Use the lower-level commands when the developer needs to inspect or edit the redacted selection before freezing it: ```sh understudy evals catalog --project --workload \ --from --to --limit 50 --seed \ --out .understudy/evals/catalog.json --json understudy evals cohort create --project --workload \ --from-catalog .understudy/evals/catalog.json --name --json understudy evals cohort export --project \ --workload --out .understudy/evals/ --yes ``` The catalog contains metadata and content hashes, never prompt/response bodies. The export is limited to the immutable cohort, verifies every downloaded body against its server-recorded SHA-256, and writes no signed URLs to disk. Do not bypass this with a project-wide R2 dump when the hosted cohort API is available. Captures may carry either `workload_id` or the older `placement_id` — read both. Then confirm with the developer which workload(s) the traces should map to, and what the unit of one "task" is (one request? one conversation?). **Profile a whole capture directory first.** When the source is a fleet of gateway captures and the developer wants to know where the spend goes and which call types a local model could take over, run the profiling playbook in [`references/profile-captures.md`](references/profile-captures.md) before (or instead of) per-workload ingestion — it produces a cost + call-type taxonomy and a ranked local-takeover candidate list from the same `.jsonl` dump. When the question is about trace *content* at fleet scale — "which runs failed", "label these by failure mode", "summarize what goes wrong" — follow with the bulk semantic-triage playbook in [`references/lotus-semantic-triage.md`](references/lotus-semantic-triage.md). ## Flow For a local, call-by-call inspection of one trace, build the bundled trace viewer first: ```sh understudy traces build-viewer \ --source .understudy/captures \ --trace-id \ --output .understudy/trace-viewer/ ``` It renders the execution timeline, system prompts, conversations, tool definitions, tool invocations/results, and raw envelopes without a server or upload. The generated `trace-data.js` contains private payloads and must stay local. See [`references/trace-viewer.md`](references/trace-viewer.md) for the input aliases, output contract, and privacy boundary. For multi-turn tool workloads, start the deterministic foundry with: ```sh understudy traces build-benchmark \ --source .understudy/captures \ --output .understudy/benchmarks/latest \ --max-age-days 3 ``` Add `--workload ` whenever the capture directory contains multiple workloads, and keep the default ten-row resumable batches. The CLI helpers are the canonical implementation; do not recreate their normalization, DAG, manifest, viewer, review, environment, or replay logic in an ad-hoc script. Follow [`references/trace-foundry-cli.md`](references/trace-foundry-cli.md) for the complete compile → review → replay lifecycle. This fails closed when no capture falls inside the requested freshness window. It writes normalized captures, a source DAG, machine-proposed tasks and outcome contracts, a canonical benchmark manifest, and a local Design Language v2 viewer. The viewer defaults to parsed JSON, retains an explicit Raw view, and loads individual private captures lazily from disk. The machine should make its strongest supported proposal immediately. Human review supplies final judgment and focuses on close calls; it does not manually author every environment. Captured incumbent behavior is evidence, never the sole oracle, and outcome contracts grade semantic final state rather than exact trajectory reproduction. 1. **Classify deterministically.** Bucket every trace into workload groups by content-based rules, never hand-picking: match on stable markers in the request (a system-prompt heading, a template name, an endpoint). Record the exact pattern used per group so the classification is auditable and re-runnable. 2. **Filter to the replayable unit.** Keep the calls that constitute the task (e.g. single-turn extraction calls with a completed stop reason); drop scaffolding (sub-agent spawns, retries, health probes). The lossless conversation history (`request.messages` or equivalent) is the canonical replay surface — record that invariant in the manifest; never evaluate against a lossy projection. 3. **Slice and freeze.** Per workload group, cut a dev set and a disjoint held-out set, choosing for shape diversity (size, tool mix, turn count), and freeze each as a list of relative keys with a hash. A frozen slice is never edited mid-experiment. Register the splits with [`../capture-evidence/SKILL.md`](../capture-evidence/SKILL.md) so its split/baseline contract owns them from here. 4. **Emit manifests.** Per slice: row count, token-count distribution, tool-call name/sequence distribution, the classification pattern, the freeze hash, and the privacy block — plus an eval-input manifest (rows keyed by a stable `input_id`, expected outputs/tool-calls where the trace contains them) that `optimize-workload` adapters and [`../compare-model-sweep/SKILL.md`](../compare-model-sweep/SKILL.md) can consume directly. 5. **Hand off.** Fleet-level cost/taxonomy questions → [`references/profile-captures.md`](references/profile-captures.md). "What is this workload actually doing?" → [`../understand-workload/SKILL.md`](../understand-workload/SKILL.md). Harness attachment, metric, and baseline → [`../capture-evidence/SKILL.md`](../capture-evidence/SKILL.md). ## Output Standard End with: the source shape and trace count pulled (staging path, not bucket identity); the workload groups with their classification patterns and counts; the frozen slice names, sizes, and hashes; the manifest paths written under `.understudy/ingest-traces/`; the privacy assertions (local-only, no raw bodies in manifests, review required before upload); and the recommended next skill for this workload. ## References - [`references/trace-envelopes.md`](references/trace-envelopes.md) — local versioned-envelope decoding, SSE, raw preservation, and freshness. - [`references/source-history-dag.md`](references/source-history-dag.md) — fingerprints, retries, branches, folds, mutations, and validation. - [`references/trace-foundry-cli.md`](references/trace-foundry-cli.md) — the deterministic compiler, review importer, Verifiers v1 generator, replay planner/runner, resumable artifacts, and promotion contract. - [`../capture-evidence/SKILL.md`](../capture-evidence/SKILL.md) — owns the metric/validator/baseline contract the frozen slices feed. - [`references/profile-captures.md`](references/profile-captures.md) — fleet-level cost and call-type taxonomy over the same capture set, with a ranked local-takeover candidate list. - [`references/lotus-semantic-triage.md`](references/lotus-semantic-triage.md) — content-level bulk triage (filter/label/rank/summarize all captures) with LOTUS semantic operators on a local MLX-served model. - [`../understand-workload/SKILL.md`](../understand-workload/SKILL.md) — decomposes one ingested workload before model comparison. - [`../curate-trajectories/SKILL.md`](../curate-trajectories/SKILL.md) — split provenance and leak-blocking once selections are made.