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Debugging · Version 1.3.0 · Reviewed 2026-08-02

Bazel Build Debugger

Diagnose cache-miss analysis and hermeticity debugging with evidence, explicit trade-offs, and a verification plan.

4 method steps 6 documented failure modes 5 diagnostic checks 7 quality gates

Diagnoses Bazel dependency declarations, action cache misses, sandbox failures, remote execution differences, and non-hermetic build behavior.

₹99 one-time

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What this skill helps you do

  • Cache-miss analysis
  • Hermeticity debugging
  • Remote execution failures

How Bazel Build Debugger works

You provide

Build definition, timings, and cache statistics

It inspects

Layer ordering and secret exposure for cache-miss analysis

It decides

A hermeticity debugging change that keeps every gate intact

You verify

Per-stage duration and cache hit rate re-measured

What it checks first

Bazel Build Debugger diagnoses Bazel dependency declarations, action cache misses, sandbox failures, remote execution differences, and non-hermetic build behavior. Use it when the work involves Cache-miss analysis, Hermeticity debugging, Remote execution failures.

  1. Layer ordering relative to change frequency, which determines whether the cache is ever reused.
  2. Whether the build is reproducible, or depends on floating tags and network state at build time.
  3. Image provenance and base-image currency, since most container vulnerabilities come from the base.
  4. Whether secrets enter the build context or an intermediate layer, where they persist even if deleted later.
  5. The critical path of the pipeline, distinguished from total pipeline time.

Failure modes it recognizes

  • Copying the entire source before installing dependencies, invalidating the dependency cache on every commit.
  • A secret passed as a build argument and permanently embedded in image history.
  • A `latest` base tag making builds nondeterministic and silently changing runtime behavior.
  • Running as root because the image never declared a user, expanding container escape impact.
  • A cache key that includes a timestamp, so the cache never hits.
  • Parallel jobs sharing a mutable cache and corrupting each other intermittently.

Answers it will reject

  • Adding retries to a flaky pipeline step instead of fixing the nondeterminism, which triples the failure latency.
  • Building images in the same stage as tests, shipping test tooling and credentials to production.
  • Disabling a security scan to unblock a release without recording an exception and an expiry.
  • Optimizing total pipeline duration when the critical path is a single serial step.

Decision rules it applies

  • Order build layers from least to most frequently changed, and copy dependency manifests before source.
  • Use multi-stage builds so the runtime image contains only runtime artifacts.
  • Pin base images by digest for reproducibility and update them deliberately.
  • Never weaken a gate to increase speed; make the gate faster or move it, but keep the signal.

Evidence it asks for

  • Measure per-stage duration and cache hit rate to find where the pipeline actually spends time.
  • Scan the built image and compare findings against the base image to attribute ownership.
  • Verify no secret material exists in image history with a layer inspection.

The method inside

  1. Reconstruct the symptom timeline and define what healthy behavior would look like for cache-miss analysis.
  2. Rank hypotheses for hermeticity debugging by evidence, blast radius, and ability to explain every observed symptom.
  3. Run the cheapest discriminating check for remote execution failures; update confidence only when evidence changes.
  4. Separate immediate stabilization, confirmed cause, contributing conditions, and prevention; finish with a reproducible verification.

Deliverables

  • Cache-miss analysis assessment
  • Hermeticity debugging decision and action plan
  • Remote execution failures verification checklist

Evidence requirements

  • Exact symptoms and timestamps
  • Reproduction conditions and recent changes
  • Logs, traces, metrics, code, or configuration

Quality gates

  • Every material claim traces to supplied evidence or is labeled as a hypothesis.
  • The response follows the declared deliverable contract.
  • No execution, access, measurement, or verification is invented.
  • Secrets and personal data are redacted rather than repeated.
  • The user receives a concrete independent verification step.
  • The relevant failure modes in this domain were considered rather than only the reported symptom.
  • No listed anti-pattern was recommended as a solution.

Example task

Input

The same Bazel target is cached locally but reruns on every CI build even with remote cache enabled.

Expected output

The action key includes an environment variable that changes per CI run, so every action is unique. Declare only required stable environment inputs and inspect aquery differences before blaming the remote cache...

Boundaries and compatibility

Ideal for

  • Cache-miss analysis: produce a decision or artifact grounded in supplied evidence.
  • Hermeticity debugging: produce a decision or artifact grounded in supplied evidence.
  • Remote execution failures: produce a decision or artifact grounded in supplied evidence.

Out of scope

  • Guessing a root cause from a symptom alone
  • Claiming a fix worked without test evidence

Agent compatibility

  • GitHub Copilot custom agents
  • Claude Agent Skills / SKILL.md
  • Any instruction-following chat model

Tool policy: Advisory by default. No tools are assumed. If the host provides tools, use read-only evidence gathering unless the user explicitly approves a scoped write or execution action.