fix(plugins): give block directives precedence

[synscott]

Summary

• make valid block directives take precedence over valid approve directives regardless of plugin registration order
• preserve first-wins ordering among directives with the same action
• preserve existing validation, approval fail-closed behavior, callback invocation, and public helper signatures

Problem

_get_pre_tool_call_directive_details() returned the first valid directive from the collected pre_tool_call hook results. If an approval-policy plugin was registered before a blocking policy plugin, an earlier approve could mask a later block:

approve, block -> approve
block, approve -> block

That makes policy composition depend on plugin discovery order and allows adding an approval hook to weaken an existing veto.

Fix

Collect the first valid block and first valid approve from the already-materialized hook results, then return:

1. the first valid block, when any block exists;
2. otherwise the first valid approve;
3. otherwise no directive.

All callbacks are still invoked once by invoke_hook() before selection. A selected block bypasses the human approval prompt; approve-only behavior remains unchanged and fail-closed.

Tests

Added regression coverage for:

• block precedence in both registration orders
• first block and first approve ordering
• approve rule_key preservation
• malformed block/approve results
• single hook-result collection
• suppression of the approval gate when a block exists

Focused canonical test runs on the submitted commit:

tests/hermes_cli/test_plugins.py: 122 passed
tests/tools/test_approval_plugin_hooks.py: 21 passed
tests/run_agent/ -k "tool or plugin or approval": 554 passed
tests/agent/ -k "tool or plugin or approval": 670 passed

Ruff lint, compileall, and git diff --check also pass.

Baseline limitation

The complete upstream suite is not green in this host environment. A prior full run produced unrelated dependency/environment failures that were reproduced by failure class on an unchanged worktree at the same base. This change does not touch those systems, and the affected plugin/approval/dispatch slices above pass on the submitted commit.

[teknium1]

Thanks for the focused policy-composition fix. Current main still returns the first valid directive in hermes_cli/plugins.py:2176-2194; an earlier approve is returned at hermes_cli/plugins.py:2192, before a later valid block can be evaluated. The returned approve then reaches the human gate at hermes_cli/plugins.py:2276-2295.

The proposed aggregation is consistent with the dispatcher: PluginManager.invoke_hook() already invokes every callback and materializes non-None results before selection (hermes_cli/plugins.py:1931-1946). The shared resolver is used by the current dispatch paths, including model_tools.py:1245-1278, agent/tool_executor.py:417-439, and agent/agent_runtime_helpers.py:2537-2554.

No blocking correctness or completeness issue found. This is an automated hermes-sweeper review.

[teknium1]

Closing as superseded by #118844 (#118844), commit 75e9567ca7, which fixes the same defect (you are credited there as a co-author / in the PR body).

Thanks for the contribution — the underlying problem this PR addresses has been resolved on current main. If you believe this was closed in error, please comment and we'll reopen.