Exact main fails nested Agent Spec classification in catalog_diff

[myobie]

Observation

Exact main commit 3e0129434ac214d46fc4cace94c7086ec486302f fails this repository test:

classification_only_and_nested_agent_filename_changes_are_exact

Reproduction

git switch --detach 3e0129434ac214d46fc4cace94c7086ec486302f
cargo test --test catalog_diff classification_only_and_nested_agent_filename_changes_are_exact

The test fails because catalog diff validates agents/host/worker/docs/agent.kdl as a strict Agent Spec candidate and rejects its top-level note node:

catalog fails full validation:
agents/host/worker/docs/agent.kdl [parse-error]: KDL declaration error: [unexpected-top-level-node]: canonical Agent Spec KDL only accepts top-level `agent` nodes, found `note`
agents/host/worker/docs/agent.kdl [unexpected-top-level-node]: canonical Agent Spec KDL only accepts top-level `agent` nodes, found `note`

The same failure reproduced in a separate detached worktree at the exact commit above.

Hosted check scope

The Nix package's cargoTestFlags run workspace libraries, binaries, discovery, codex_hooks, and hooks. They do not run tests/catalog_diff.rs. A successful hosted Nix check therefore does not exercise this failing test.

[myobie]

Current-main confirmation

The failure still reproduces in a clean detached worktree at exact main f177520b51d1bf0e65a0c225e48e95b1be2121be.

$ cargo test -p st2 --test catalog_diff classification_only_and_nested_agent_filename_changes_are_exact -- --nocapture
running 1 test
thread 'classification_only_and_nested_agent_filename_changes_are_exact' panicked at tests/catalog_diff.rs:80:5:
diff stderr: Error: validate live catalog for diff

Caused by:
    catalog fails full validation:
    agents/host/worker/docs/agent.kdl [parse-error]: KDL declaration error: [unexpected-top-level-node]: canonical Agent Spec KDL only accepts top-level `agent` nodes, found `note`
    agents/host/worker/docs/agent.kdl [unexpected-top-level-node]: canonical Agent Spec KDL only accepts top-level `agent` nodes, found `note`

test result: FAILED. 0 passed; 1 failed

A bisect used the same test. Commit f288c9dcac037e574efef8b330d1ecfd7868698c passes. The first failing commit is b19cb196daf65f071ee8ef50c0539dcc7efdc54b (feat(agent-spec): unify strict declaration admission).

This test does not run under nix flake check. The package cargoTestFlags select workspace libraries, binaries, discovery, codex_hooks, hooks, and run. No dedicated checks.* derivation selects catalog_diff.

A green Nix check therefore does not execute this test.