test: cover stabilized logout, provider rename, and session/delete

[cursor]

Risky behavior now covered

Three recently merged code-changing PRs landed with under-tested surfaces. This adds focused regression tests that lock in their wire contracts and fault-tolerance behavior in both v1 and v2 type namespaces.

1. logout (stabilized in agentclientprotocol#1273) — previously zero direct tests

• Wire method name (AGENT_METHOD_NAMES.logout, LOGOUT_METHOD_NAME).
• ClientRequest::LogoutRequest(...).method() routing.
• LogoutRequest / LogoutResponse (de)serialization, including _meta round-trip and the empty-object shape that on-the-wire peers depend on.
• auth.logout capability advertisement ({} / None) on AgentAuthCapabilities.
• DefaultOnError fault-tolerance contract on auth.logout: a malformed value (string, number, bool, array, wrong-typed _meta) must fall back to None instead of poisoning the entire initialize response. This is the defensive behavior the field was annotated for, and it had no test.

2. providers/{set,disable} rename to singular (agentclientprotocol#1272) — previously no method-routing test

• Asserts AGENT_METHOD_NAMES.providers_{list,set,disable} and their constants.
• Asserts ClientRequest::{ListProviders,SetProvider,DisableProvider}Request.method() returns the renamed wire names. A future accidental rename in either spot now fails loudly instead of breaking the wire silently.

3. session/delete (added in agentclientprotocol#1216, feature-gated) — missing cross-namespace round-trip

• v1 <-> v2 conversion round-trip for DeleteSessionRequest and DeleteSessionResponse (including _meta) so gateways bridging the two namespaces can't silently drop the payload.

Bonus: cross-namespace round-trips

• LogoutRequest / LogoutResponse round-trips (v1 <-> v2, with and without _meta).
• AgentAuthCapabilities round-trips both with and without the logout capability (the latter guards against None flipping to Some(default), which would silently flip every agent into "supports logout").
• SetProviderRequest / DisableProviderRequest round-trips.

Test files added/updated

• src/v1/agent.rs — 5 new tests in test_serialization (logout × 4, provider routing × 1).
• src/v2/agent.rs — same 5 tests mirrored into the v2 type namespace.
• src/v2/conversion.rs — 5 new round-trip tests covering logout, AgentAuthCapabilities (with and without logout), feature-gated session/delete, and feature-gated provider set/disable.

Why these tests materially reduce regression risk

• Largest blast radius: every ACP peer reads initialize and AGENT_METHOD_NAMES. A method-name drift or a malformed capability silently disables a feature for everyone, not just one caller.
• Stabilized surface, zero coverage: logout moved out of the unstable feature flag without picking up a single direct test; this fills that gap before drift accumulates.
• Singular-rename regression: a future rename or refactor of providers/set/providers/disable constants or enum-routing would have shipped without complaint. Now it fails the test suite.
• Cross-namespace parity: v1 <-> v2 conversion is the most fragile invariant in this repo (the file is ~9.5k lines of hand-rolled field-by-field code); the new round-trips for logout / capabilities / session-delete / provider messages catch dropped fields and shape drift the moment they appear.

Validation

• cargo test --all-features --lib → 283 passed (was 268).
• cargo test --lib (default features) → 45 passed.
• cargo test --features unstable_llm_providers --lib and cargo test --features unstable_session_delete --lib both green for the feature-gated tests.
• cargo clippy --all-features --lib --tests → clean.
• cargo fmt -- --check → clean (post-format).
• All new tests are deterministic (pure (de)serialization + type-level assertions, no I/O, no time, no parallelism dependencies).

No production code was changed.

  

---

Summary by cubic

Add regression tests for stabilized logout, singular provider methods, and session/delete across v1 and v2 to lock in wire method names, request/response {} shapes and _meta, and ClientRequest routing. Asserts auth.logout capability behavior (advertised as {}, missing → None, malformed → None via DefaultOnError) and adds v1↔v2 round-trips for logout, capabilities, provider set/disable, and session/delete; no production code changed.

^{Written for commit 4bf249d. Summary will update on new commits.}

Note

Add test coverage for logout, provider rename, and session delete across v1/v2

• Adds serialization and routing tests for LogoutRequest/LogoutResponse in both v1 and v2, verifying wire method names and _meta round-trips.
• Adds tests for AgentCapabilities auth logout serialization, including fault-tolerant deserialization of malformed values via DefaultOnError.
• Adds v1↔v2 conversion round-trip tests in conversion.rs for logout, session delete (unstable_session_delete), and provider set/disable (unstable_llm_providers).
• Adds provider method name tests asserting singular form constants and correct ClientRequest routing under the unstable_llm_providers feature flag.

^{Macroscope summarized 4bf249d.}