Two findings from KeiSeiKit2.0 pr-review (~/Projects/KeiSeiKit2.0/skills/pr-review)
applied to commit range b346250..HEAD.
1. BLOCKER — SecretString silently leaked plaintext via Serialize.
File: _primitives/_rust/kei-runtime-core/src/secrets.rs
Was: derive(Serialize) + serde(transparent) -> serde_json::to_string(&secret)
emitted the raw plaintext in any parent struct with #[derive(Serialize)].
Debug was redacted but Serialize was not. Defeated the type's purpose.
Now: manual Serialize impl always emits literal "<redacted>". Deserialize
derive kept (callers need to read secrets from config/env).
Test serialize_emits_redacted_literal asserts JSON output is "\"<redacted>\"".
2. WARNING — PKCE code_verifier dropped before token exchange.
build_auth_url generated code_challenge = SHA256(verifier) but verify() never
threaded the verifier to the token endpoint. Token exchange submitted no
code_verifier, defeating the PKCE protection.
Files:
- _primitives/_rust/kei-runtime-core/src/traits/auth.rs:
AuthChallenge::OAuthCode now carries code_verifier: Option<String>.
Caller stores verifier alongside state in their session-store, exactly as
they already store state for CSRF check.
- _primitives/_rust/kei-auth-google/src/provider.rs:
verify() destructures code_verifier and passes to client.exchange_code(...).
- _primitives/_rust/kei-auth-apple/src/provider.rs:
same change.
Tests added (wiremock body assertions):
- google_smoke / apple_smoke: assert exchange request body contains
code_verifier=<value> when challenge carried Some(verifier).
- existing tests updated to construct OAuthCode { ..., code_verifier: None }.
Test split (Constructor Pattern 200 LOC):
- apple_smoke.rs grew over 200 LOC after PKCE test addition. Split into
apple_smoke.rs (provider tests) + apple_client_smoke.rs (client tests).
- same for google_smoke.rs / google_client_smoke.rs.
Test results: 31 passed; 0 failed across kei-auth, kei-auth-apple, kei-auth-google,
kei-runtime-core unit + integration tests. cargo check --workspace clean.
Breaking change: any caller that constructs AuthChallenge::OAuthCode outside this
workspace must add code_verifier field (None for legacy no-PKCE; Some for PKCE).
Compile-time surfaced gap, not runtime regression.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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