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 as it works
• Clearing findings before handoff is a deterministic run, not a remembered intention — see Gate It Deterministically
• 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)
• Before handoff, the agent runs the same gate command CI runs and clears every finding, scoped to the changed set only where the gate supports it
• The LSP tool is the live editor surface for those findings as the agent works
• The pre-handoff run makes "cleared before handoff" a checkable event
• CI runs the same gate as the backstop, never the first place a finding surfaces
• A Stop or pre-handoff hook running the gate mechanizes this where the harness supports it

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