[backryun]

Part of #8484. All five diagnostics in chatCore/semanticCache.ts, one cause — the function's own parameter list.

Declared unknown, then read through

clientRawRequest: unknown;      →  clientRawRequest?.headers
reqLogger: unknown;             →  reqLogger.logConvertedResponse(…)
log: unknown;                   →  log?.debug?.(…)
effectiveServiceTier: unknown;  →  passed where a string is expected
body: Record<string, unknown>;  →  body.temperature / body.top_p

The last one is the least obvious: they go into generateSignature(model, conversation, temperature = 0, topP = 1, …), whose defaults infer number, so unknown from the index signature will not fit.

Fix

Named only the fields this read path actually touches:

body: Record<string, unknown> & { temperature?: number; top_p?: number };
clientRawRequest: { headers?: unknown } | null;
reqLogger: { logConvertedResponse: (response: Record<string, unknown>) => void };
effectiveServiceTier: string | null | undefined;
log: { debug?: (...args: unknown[]) => void } | null;

Everything else on the request body stays unknown behind the index signature — this is not an attempt to type the whole chat body, just to stop the parameters lying about what the function does with them.

No casts added, no call site changed, nothing executable touched.

Verification

208 → 203, zero new errors, on a line-number-agnostic diff of the full tsc error set.

• npm run typecheck:core — clean
• eslint, check:file-size — clean
• 401/401 across the 47 cache suites

No new tests

Parameter declarations matching how the arguments were already being used — no control flow altered, no runtime diff. reqLogger.logConvertedResponse is called unconditionally so it is declared required; log.debug is called with ?. so it stays optional, which is what the existing callers already pass.

[diegosouzapw]

Validated in local merge-train /tmp/train1d-20260727-090022-suite.log on .113 @ 029cdf4215cf465f0e1716ac9f84a84692b1e881 (full unit suite green on CI-equivalent host)