Organize tests by capability ownership

Traceability

• Spec ID: test-suite-capability-layout
• Status: Implemented

Intent

Replace the flat test/ directory with a small capability-oriented hierarchy so maintainers can find the tests owned by the production area they are changing. Keep Node-native recursive test discovery, focused test commands, fixtures, and cross-platform behavior intact.

Acceptance Scenarios

• AC-1: Every active *.test.mjs file lives in exactly one documented capability directory: agents, cli, governance, learning, plugins, reporting, sessions, or skills-docs.
• AC-2: npm test recursively discovers only moved *.test.mjs files without maintaining a second hand-written test manifest or executing fixture modules.
• AC-3: Imports, import.meta.url resources, repository-root fixtures, and CLI paths resolve on Windows, macOS, and Linux after the extra directory level.
• AC-4: Active repository instructions and code comments use the new paths; historical specs retain their original evidence paths as historical records.
• AC-5: test/fixtures remains a shared, non-test resource directory and is not duplicated inside capability folders.
• AC-6: The focused category commands, full suite, package verification, and whitespace checks pass from the repository root.

Non-goals

• Reclassifying tests as unit, integration, or end-to-end when one file crosses those execution levels.
• Splitting large test files or changing production behavior in the same change.
• Rewriting historical specs merely because their recorded test paths predate the new layout.
• Moving shared fixtures away from test/fixtures.

Plan and Tasks

1. Document category ownership in test/README.md with focused commands.
2. Move each active test to the directory matching its primary production owner; prefer one obvious home over duplicated or nested taxonomies.
3. Mechanically update imports from repository modules and the one import.meta.url fixture reference affected by the extra path level.
4. Update active instructions, references, and code comments that invoke exact test paths.
5. Verify each category is discovered independently, then run the complete suite and real package verification.

Test and Review Evidence

• AC-1/AC-5: inventory test/**/*.test.mjs, confirm the root contains no test files, and compare the moved-file count with the pre-move active count.
• AC-2/AC-3: npm test plus focused node --test "test/<category>/*.test.mjs" commands.
• AC-4: repository search for active references to old flat test paths.
• AC-6: npm run pack:verify and git diff --check.
• Risk: path-only moves can hide a missing test if default discovery changes; category counts and the full-suite test total must be inspected, not only the process exit code.

Implementation Evidence

• All 90 active *.test.mjs files moved from the flat root into eight owner directories: agents 10, CLI 5, governance 11, learning 7, plugins 12, reporting 24, sessions 17, and skills/docs 4. The test/ root now contains zero test files, while test/fixtures remains shared.
• Node 24 rejected directory operands, so focused commands use quoted native globs such as node --test "test/sessions/*.test.mjs"; the plugins and skills/docs focused run passed.
• Four missed repo-root calculations initially caused seven path failures. After repairing those seams, their focused rerun passed 21/21. A later Git timeout under two concurrent full-suite processes passed 29/29 when rerun without resource contention.
• Final npm test -- --test-reporter=tap passed 1301/1301. The explicit test/**/*.test.mjs discovery removed two fixture helper modules that the old default discovery incorrectly executed as tests.
• node --test test/skills-docs/doc-link-graph.test.mjs passed 6/6 after graph regeneration. npm run pack:verify passed with 505 npm entries and 527 runtime ZIP entries; git diff --check passed.