Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[0.4.1] - 2026-07-30

Fixed staged execution so the aggregate in-flight command count never exceeds the largest stage max_concurrency. In 0.4.0, each stage enforced its limit independently, so pipelined stages could exceed -j N in aggregate and -j 1 was not actually serial.
Fixed parallelism.overrides so a task-specific value can lower parallelism.max_concurrency. The workspace value is now a ceiling and the default for tasks without a task-specific limit; explicit CLI -j remains the highest-precedence pin.

Added parallelism.max_concurrency as a supported workspace configuration key that explicitly pins the effective concurrency of every workspace task. Effective concurrency now resolves as CLI -j/--max-concurrency, then parallelism.max_concurrency, then parallelism.overrides, then round(base * multiplier), then 1.
Added Blitz.run_stages/2 and Blitz.run_stages!/2: staged command execution without barriers between stages. Commands form per-id pipelines — a later-stage command starts once every same-id command in earlier stages succeeded — while each stage keeps its own max_concurrency bound. A failure blocks same-id downstream commands and stops new launches.

Changed Blitz.MixWorkspace.run!/3 and the impact runners (Blitz.MixWorkspace.Impact.run!/4 and run_many!/3) to execute their planned stages through Blitz.run_stages, so task families overlap per project instead of forming workspace-wide barriers. A project's test can start as soon as that project's compile succeeded while other projects are still compiling; result persistence, summaries, and failure semantics are unchanged.
Changed workspace configuration validation to reject unknown keys in blitz_workspace, parallelism, isolation, and per-task configs with an error listing the supported keys. Previously a misspelled key (for example parallelism.max_concurency) was silently ignored and could degrade the workspace to concurrency 1.

Removed parallelism.env. Configuring it now raises with a migration message pointing at -j/--max-concurrency or parallelism.max_concurrency.

Fixed the Blitz.MixWorkspace moduledoc to state the real concurrency resolution order; it previously claimed per-task overrides took precedence over the workspace max_concurrency pin.

Added impact-aware Blitz.MixWorkspace.Impact planning and execution for task-state based workspace CI.
Added .blitz/test_state_v1 persistence with a compact exact task-state index for passed-result reuse.
Added deterministic project, dependency, command, environment, and workspace hashing for Mix workspace tasks.
Added mix blitz.workspace.impact for dry-runs, forced runs, and base/head change planning.
Added mix blitz.test_state.prune for manual compact-store cleanup.
Added clean-commit pipeline manifests for fast run_many! skips when an identical clean workspace CI pipeline has already passed.
Added clean-baseline ledgers for baseline-aware dirty workspace planning.
Added machine-readable decision coverage sources for exact task-state, clean-baseline, impacted, forced, and missing-baseline outcomes.
Added unlocked Git dependency safeguards so unpinned Git dependencies without lockfile entries do not receive reusable deterministic skip evidence.
Added guides for impact CI, persisted test state, and downstream integration.

Expanded HexDocs extras and package files to include the new guides.
Changed default test-state retention from audit-style append streams to a compact local cache. Append-only results.ndjson and per-commit streams are now opt-in with BLITZ_TEST_STATE_RETENTION=audit.
Changed Blitz.MixWorkspace.Impact.run_many!/3 to snapshot workspace state once for the whole task list instead of replanning each task independently.
Changed dirty-worktree planning to skip unimpacted project/task states when the current task state is covered by the latest clean baseline.
Changed project dependency snapshots to include parsed mix.lock entries where available while still treating local path dependencies as source fingerprints.
Changed deps_get task-state hashing to use dependency declaration state instead of dependency execution state, so local path dependency source edits do not force dependency fetches for reverse dependents.
Changed dry-run baseline skip text to distinguish clean-baseline coverage from exact dirty-state memoization, including the coverage source and baseline availability for each decision.

Ignored .blitz/** in git dirty-state, changed-file, and repo-file discovery so the test-state store cannot make itself look like impacted source input.
Fixed mix.lock changes so lockfile output churn does not automatically select deps_get; dependency-sensitive tasks still rerun for the owning project and reverse local dependents.
Fixed source-change impact planning so deps_get stays skipped unless a dependency declaration or project mix.exs changes.
Fixed first dirty-run coverage for child README and source edits with root test splitting, including root projects that depend on child path packages.
Fixed workspace invalidator handling so files such as build_support/dependency_resolver.exs and build_support/workspace_contract.exs are fingerprinted into the workspace task state and cannot be hidden by previously covered exact task states.

Enriched Blitz.Result with bounded output_tail, explicit failure_kind, and structured failure metadata used by Blitz.Error.
Reworked Blitz.Error to render actionable failure summaries with command, cwd, duration, reason, and a bounded output excerpt.
Changed timeout handling to return structured timeout failures instead of exiting the caller process.

Preserved the last output lines for failing commands so callers do not need a second repro to inspect the likely root cause.
Reported worker crashes distinctly from normal non-zero command exits.