Measure quality, speed, and memory envelope

Add executable validation at the trust boundaries of Ollama-backed local router with policy-controlled cloud fallback. Reject unknown fields where they matter, bound string sizes, and coerce only after auth/signature checks when raw bytes are security-relevant. Invariant under test: cloud fallback requires explicit policy flag + redaction pass; local p95 ≤ 6s for 512 tokens. A TypeScript type or Python annotation is not runtime validation — pair them with parsers.

Automate the fixtures from setup, including a recreation of LOCAL-FALLBACK-PII-03. Assert both the visible error and the absence of side effects (no provider call, no queue write, no flag flip). Where metrics matter, assert label enums stay bounded.

Document which failures are client mistakes (4xx) versus operator/config mistakes (5xx/503). Oracle still stands: local llama3.2:3b answers fixture brief at ≥ 25 tok/s; fallback path logs reason=local_timeout. Validation should make accidental “success with empty body” impossible for legal analyst summarizing NDAs that must not leave the laptop by default.

Property ideas: shuffled field order, Unicode edges, maximum-length strings, and replayed timestamps. Where money, identity, or citations matter, assertion messages should cite the field name. Do not snapshot entire provider payloads in tests; assert semantically. If validation fails open “to keep the demo working,” you have inverted the lab. Tie at least one CI job to the LOCAL-FALLBACK-PII-03 fixture so main cannot regress silently. Re-read cloud fallback requires explicit policy flag + redaction pass; local p95 ≤ 6s for 512 tokens after each new parser — convenience helpers love to bypass it.

Table-drive status codes and error codes so reviewers see coverage at a glance. Include a Unicode normalization case if user text is accepted. Verify that oversized bodies fail before CPU-heavy work. Where digests or versions are pinned, assert mismatch behavior. Keep golden files small enough to read in review. CI should fail on skipped tests that mark the incident fixture as xfail without a ticket link. In this chapter the product is Ollama-backed local router with policy-controlled cloud fallback, the human stakeholder is legal analyst summarizing NDAs that must not leave the laptop by default, and the incident id you design against is LOCAL-FALLBACK-PII-03. Re-state the oracle in your notes — local llama3.2:3b answers fixture brief at ≥ 25 tok/s; fallback path logs reason=local_timeout — and keep the invariant visible: cloud fallback requires explicit policy flag + redaction pass; local p95 ≤ 6s for 512 tokens. Track local_share ≥ 0.8 and cloud_fallback_with_pii == 0 as the scoreboard. Surface under change control: POST http://127.0.0.1:11434/api/generate. If you only have forty minutes, finish the fixture for fallback silently ships full NDA text to cloud when Ollama is down before polishing UI. Promotion language stays ternary: promote, hold, or roll back based on evidence, not hope.