v3.15.2

Testing

• Test(mcp): extract grouping helpers + 36 new tests (31 unit, 5 dispatch)

Motivation: the answer_mode=1 refactor added autoGroupByHeuristic() and
rewrote splitPerFileSections(), but neither had unit tests and the
helpers lived inside index.ts (which has top-level server.connect()
side effects that make direct import unsafe). This commit extracts the
helpers into a pure module and adds 36 tests.

1. New file: mcp-server/src/grouping.ts

   • Moved parseFileGroups, hasNamedGroups, autoGroupByHeuristic,
     splitPerFileSections, GROUP_HEADER_RE, GROUP_FOOTER_RE, FileGroup,
     and the private helpers (sanitizeGroupId, uniqueGroupId,
     statFileForGrouping, splitBucketBySize, splitBucketByBasenamePrefix)
     out of index.ts.
   • Module has zero side effects — only imports from node:fs and
     node:path — so tests can require it without booting the MCP server.
   • index.ts now imports from ./grouping.js.

2. New file: mcp-server/src/grouping.test.ts — 31 unit tests
   parseFileGroups (7):

   • empty input
   • unmarked paths → single unnamed group
   • single named group
   • multiple named groups preserve order
   • header closes previous group without explicit footer
   • files outside markers go into id=""
   • empty named groups dropped
     hasNamedGroups (3): all-empty, at least one named, empty array
     autoGroupByHeuristic (10, uses real tmp files on disk):
   • empty input
   • filters ---GROUP:id--- markers defensively
   • same-ext files in same dir → one group
   • different extensions in same dir → separate groups
   • different dirs with same ext → separate groups
   • nested subdirectories get their own group
   • stable deterministic ids across invocations
   • single file input
   • oversized bucket splits via FFD with -p{n} suffix
   • duplicate dir-name collision → unique _2 suffix
     splitPerFileSections (11):
   • empty input
   • no ## File: headers → empty map
   • exact-path matching
   • suffix matching (dropped directory prefix)
   • basename matching
   • Windows CRLF line endings (trailing \r stripped by .trim())
   • backtick/quote decorations around path
   • missing sections omitted from map
   • duplicate header → first section kept
   • trailing --- separator trimmed
   • single-file section without separator

3. New tests in index.test.ts — 5 answer_mode dispatch integration tests

   • chat mode 1: mixed-extension files route through auto-grouping
     without pre-LLM validation errors
   • code_task mode 1 + explicit ---GROUP:id--- markers: routes through
     the explicit grouped path
   • scan_folder mode 1: validates nonexistent folder BEFORE any LLM call
   • chat mode 2: regression guard for the single-merged-report path
   • search_existing_implementations mode 1: validates feature_description
     before the grouping step runs

4. vitest.config.ts — include grouping.test.ts in the default run.

Validation:

• typecheck: ok
• lint: 0 warnings
• build: ok
• npm test: 54/54 pass (31 unit + 23 integration, 18 pre-existing + 5 new)
• grouping unit tests run in 6 ms

Note: the original index.ts was ~10k lines with scattered helper
definitions; extracting the grouping module also trims ~270 lines of
duplicated code from the main file.