The MCP mocks test in #387 used an empty schemaVersion and expected
the 1.1 error path. Because LoadEvalSpec normalizes empty schemaVersion
to the current version (1.1), the test passed validation instead of
failing. Make the test explicit by setting schemaVersion: '1.0' to
actually trigger the gate, then bump to '1.1' in the second half.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

#388)

* feat: per-task tool metrics with structured arg matchers (closes #366)

- Add argmatcher package (equals/regex/contains/range/json_schema)
- Extend tool_calls grader with expect: [{tool, args}] block
- Extend tool_constraint grader with args: matchers on expect_tools
- Add normalized tool_events[] to RunResult (turn, sequence, tool_call_id,
  tool_name, args, result, success, duration_ms, error) populated from
  session events — replay-friendly for Wave 3 (#367), OTel-aligned
- Bump results.json schemaVersion to 1.1 (MINOR additive per #368/#382)
- waza compare prints aggregate TOOL USE section (total calls, success
  rate, avg/task, histogram, selection accuracy) when tool data present
- Unit tests for matchers, builder, both graders, schema round-trip,
  compare metrics + histogram
- Docs: graders.mdx (expect/args), schema-changes.md (1.1 entry),
  cli.mdx (compare TOOL USE), README.md

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: address Copilot review feedback on #388

- graders.mdx: matchers are single-key mappings (no kind field);
  graders evaluate session_digest.tool_calls (not tool_events[]);
  range matcher uses gte/lte/gt/lt (not [min, max]).
- tool_events.go: stringifyResult comment matches JSON-only behavior.
- cmd_compare.go: histogram bucketed per-run (not truncated per-task avg);
  added 'Tasks w/ tools' row; renamed 'Tasks w/' to 'Runs w/' labels;
  use tagged switch on runCalls.
- schema-changes.md / README.md / schema.mdx: missing schemaVersion is
  interpreted as the current schema version (1.1), not 1.0.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* test: fix MCP mocks schemaVersion test after rebase

The MCP mocks test in #387 used an empty schemaVersion and expected
the 1.1 error path. Because LoadEvalSpec normalizes empty schemaVersion
to the current version (1.1), the test passed validation instead of
failing. Make the test explicit by setting schemaVersion: '1.0' to
actually trigger the gate, then bump to '1.1' in the second half.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: address round-2 Copilot review on #388

- persist compiled matcher in validateToolSpecs (map value semantics)
- capture engine-specific tool args via ToolCallArgs.Extra (mapstructure ',remain')
- bucket call_count_histogram per-task across trials (not per-run)
- rename TOOL USE table label 'Runs w/' -> 'Tasks w/' to match metric
- sync README tool_events[] field list with ToolEvent struct
- add IsCompiled() accessor + tests for persisted compile, extra args, and
  per-task histogram with trials_per_task > 1

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>