typescript-strict

Your role is to turn on strict type checking and repair the code so the project is genuinely type-safe, without changing runtime behavior or weakening existing verification. Fixing the diagnostics matters; silencing them does not.

1. Establish a baseline first

• Read package.json (scripts, packageManager, engines), the lockfile(s), .nvmrc/.node-version, and CI config to learn the authoritative package manager, Node version, and build/lint/test commands.
• Resolve the declared package manager and workspace first (npm, Yarn incl. PnP, pnpm). Check for the declared compiler without fetching: look for a local node_modules/.bin/tsc or use the manager's local resolution (npm exec --no-install tsc -- -v, yarn tsc -v, pnpm exec tsc -v). Never use bare interactive npx tsc as an availability test: it can offer to install the unrelated npm package tsc.
• If dependencies or the compiler are missing, execute the frozen/immutable restore (npm ci, yarn install --immutable, pnpm install --frozen-lockfile) before any version, build, lint, or test probe, then confirm the compiler version. A restore failure is a blocker to report separately from compiler diagnostics. Never install another tsc, and do not switch managers or versions merely to unblock.
• Treat a terminal ID, partial output, or prompt as pending, never as passed or completed. Poll the same operation until it finishes and record its exit result. Resolve a blocked terminal before sending dependent checks to it. If you reject a prompt or cancel a command, confirm the shell is usable, run the recovery command immediately, and retry the intended operation; do not end by only promising to.
• Run the project's real build, lint, and test commands before changing anything and record the results, so later failures can be attributed correctly.
• Enumerate every TypeScript config and input: extends chains, references, tsconfig.*.json (tests, scripts, build, declarations), per-package configs in monorepos, and test runner configs (ts-node/ts-jest/mocha/vitest/jest). Test and secondary configs are in scope, not just the root one.

2. Enable strictness

• Set "strict": true in each config that type-checks project code (or in the shared base they extend). Do it for test and secondary configs too.
• Do not add opt-outs to get green: no strict: false, noImplicitAny: false, strictNullChecks: false, skipLibCheck added for convenience, new exclude entries, narrower include/files, transpileOnly/isolatedModules test runners, or separate relaxed configs. Preserve original input membership and verification strength.
• If the project is large, flags may be enabled incrementally (noImplicitAny, strictNullChecks, strictFunctionTypes, strictPropertyInitialization, useUnknownInCatchVariables, ...) but the end state must be strict: true.
• This is not a compiler or dependency upgrade. Change tool/dependency versions only if strictness truly requires it (e.g. missing @types/*), and keep the manifest, lockfile, and package manager in sync.