Language Diagnostics

Enable the Language Server

• Every project turns on the diagnostics engine appropriate to its language — pyright/pylance for Python, tsserver/tsc for TypeScript, rust-analyzer/clippy for Rust, gopls/go vet for Go, and the like
• Enable it in-editor for the human and in-loop for the agent — Claude Code and other coding CLIs expose the language server (the LSP tool here), so the agent reads diagnostics on the files it touches and clears them before handing work off
• Configure the engine for the project's module layout so references resolve (see Resolve Modules First)
• Use whatever engine the project already has — don't introduce a second one without consensus

Findings Are Non-Dismissible Without Cause

• A diagnostic is fixed, or suppressed inline with a stated reason — never silently ignored
• The cause rides next to the suppression — a one-line comment naming why the finding is wrong or unreachable, not a bare ignore directive
• No blanket or file-wide silencing — # type: ignore, # pyright: basic, // @ts-nocheck, //nolint:all switch the engine off for a whole file and mask the same signal it exists to catch
• Prefer a typed helper that proves the invariant once over scattered ignores

Gate It Deterministically

• CI runs the engine's headless/CLI form — pyright CLI, tsc --noEmit, clippy, go vet — as a gate at zero findings
• The language server is the editor surface; the gate runs the same engine in batch mode, before tests, alongside format/lint (see rules/code-formatting.md CI Integration)
• "Don't ignore the warnings" enforced by an agent's or contributor's memory is not a gate — a deterministic check nobody runs does not exist (see rules/script-delegation.md)

Resolve Modules First

• Configure the engine so imports resolve before turning strictness up — unresolved modules stop deep checking, so real bugs hide behind resolution false-positives
• Match the config to the project's module layout — pyright executionEnvironments with per-root extraPaths for Python path-insert bundles; tsc baseUrl/paths/project references for TS workspaces
• Resolution is what unlocks the real findings — null/undefined-flow crashes, could-be-null raise/throw, Optional/nullable misuse

Adopting on a Dirty Tree

• Turning the gate on for a tree never checked is its own focused change — land the config plus the fixes in a PR separate from feature work
• The tree goes green first; wire the gate into CI only once it reports zero findings
• Sequence large adoptions: a config PR, then fix PRs grouped by finding shape, then the CI-gate PR