Checks

strider check is the single diagnostic command. It combines formatting drift, source-level policy, and package-aware correctness findings in one globally sorted report. It is read-only unless --fix or --fix-unsafe is requested. Files and parsed source are shared across selected checks, while more expensive program information is prepared only when a selected check needs it.

Syntax trees, type information, and control-flow representations are internal scheduling capabilities. They do not create separate commands, configuration sections, or rule namespaces, and a check can change implementation without changing its public code.

Run checks

Run every check at or above the configured severity floor. The default warning floor runs 191 checks:

strider check [PATH]...

Run all 207 checks whose effective severity is note or higher:

strider check --minimum-severity note [PATH]...

Run exactly a subset of codes:

strider check --only format --only no-init --only invalid-regexp [PATH]...

Comma-separated codes are equivalent:

strider check --only format,no-init,invalid-regexp [PATH]...

Explicit selection is case-insensitive and retains configured severities, the minimum-severity threshold, and path exclusions. It also lets Strider avoid preparing capabilities the selected checks do not need.

Run only checks whose effective severity is warning or higher:

strider check --minimum-severity warning ./...

Selection happens first, then per-rule severity overrides, then the minimum threshold (none < note < warning < error). --only does not bypass the threshold. Checks filtered this way are omitted before Strider plans CST, type, or SSA work.

Keep an incremental text-mode session open while editing:

strider check --watch ./...

Watch mode reports the initial generation, then emits a fresh complete report when selected source or its package boundary changes. It reuses unchanged CST results and only accepts cached package findings after confirming the complete analysis fingerprint. Baseline generation and pruning, JSON, and HTML are one-shot operations and cannot be combined with --watch.

Apply automatic fixes

Apply only automatic fixes explicitly classified as safe:

strider check --fix [PATH]...

Include safe, potentially unsafe, and unsafe automatic fixes:

strider check --fix-unsafe [PATH]...

The short forms are -x and -u. The two modes are mutually exclusive and cannot be combined with watch mode, baseline generation, or baseline pruning. The initial automatic set is format, double-negation, redundant-switch-break, and single-argument-append.

Text reports put a * directly after checks with an automatic fix. Green marks safe fixes and purple marks fixes that require --fix-unsafe; the same markers appear in the per-check list, and the final issue summary counts both kinds.

Fix selection happens only after --only, effective severity, path exclusions, source suppressions, and the active baseline have removed ineligible findings. Baselined or suppressed findings are therefore not changed. Strider chooses an explicitly automatic fix at the requested safety level, composes edits per file, and skips every nonidentical overlapping fix with a warning. It then formats affected source unless formatter exclusions or the file’s format-ignore directive opt it out, and validates that the result parses. A batch containing safe changes also type-checks against an in-memory overlay before anything is written.

The analyzed source is retained as a content snapshot. Every analyzed file is compared after staging and before the first replacement, so a change detected then aborts the whole batch as stale. Each write target is checked again immediately before its replacement. After a successful application, Strider runs the selected checks once more and reports what remains. Exit 0 means the rerun is clean, exit 1 means findings remain, and exit 2 means selection, validation, stale-source detection, or writing failed.

All outputs are staged before the first replacement, and each file replacement is atomic. The batch is not a filesystem transaction: if a later rename fails or a concurrent edit is detected after commit starts, an earlier replacement can remain committed. Permission bits are preserved; ownership, ACLs, and extended attributes depend on the host filesystem. A directly named source symlink is kept and guarded against retargeting while its captured target is updated.

Safe means the transformation is designed to preserve Go program semantics. Parsing and type-checking provide strong guards against invalid output, but they cannot prove identical observable behavior under every toolchain, build tag, platform, or environment. Review unsafe fixes according to the code and deployment contexts that matter to the project.

Discover checks

Inspect the checks admitted by the effective severity floor:

strider check --list-checks
strider check --minimum-severity none --list-checks
strider check --explain invalid-regexp

Strider includes one reserved format check, 94 style and maintainability checks, and 112 correctness and data-flow checks. Individual check pages are grouped by purpose in the documentation sidebar.

Configure checks

Every check code accepts severity and path excludes under the version-1 [checks.rules] namespace:

version = 1

[checks]
minimum-severity = "warning"

[checks.rules.format]
severity = "note"

[checks.rules.file-length-limit]
severity = "error"
max-lines = 800
excludes = ["testdata/golden/**"]

[checks.rules.possible-nil-dereference]
severity = "error"

[checks.rules.no-init]
severity = "none"

The tool-wide minimum severity, exclusions, and default baseline live under [checks]. Formatter layout and formatter-only exclusions remain under [formatter]. See Configuration for the complete contract.

Formatting findings

Formatting participates as code format. An unformatted file produces a normal note at the start of the file, with a green * marking its safe automatic fix:

format*: file is not formatted
  ┌─ main.go:1:1
  │
1 │ package main
2 │

Without a fix flag, check never writes the formatted candidate. Use strider fmt, or strider fmt --diff to inspect the change. check --fix applies the same validated candidate. Formatting findings are not captured by baselines.

Reports

Text is the default human-readable report format:

no-init: replace init with explicit initialization
   ┌─ main.go:12:6
   │
11 │
12 │ func init() {
13 │     configure()
 
no-init  1
1 issue: 1 note

Use JSON for integrations or HTML for a self-contained artifact:

strider check --format json ./...
strider check --format html ./... > check-report.html

Each JSON diagnostic includes code, message, severity, file, start, and end; diagnostics may also carry notes and suggested remedies. HTML reports include severity totals, search, filters, and source context without external assets or timestamps.