t1345: Fix markdown-formatter MCP tool — 100% error rate

.agents/prompts/build.txt

@@ -108,12 +108,14 @@ When referencing specific functions or code include the pattern `file_path:line_
 - If webfetch returns 404/403, do NOT retry the same URL or a variation. The URL was likely constructed/guessed. Find an alternative source (gh api, context7, ask the user).
 - If webfetch returns 429 (rate limited), wait before retrying. Do not make multiple rapid requests to the same domain.
 #
-# 2. markdown-formatter exit codes (6 uses, 100% "failure" rate — expected behavior)
-#    Root cause: markdown-formatter exits non-zero when it finds lint issues —
-#    this is expected linter behavior, not a tool failure.
-- markdown-formatter exit code 1 means "issues found", not "tool broken". Read the output for the actual findings.
-- NEVER retry markdown-formatter expecting a different exit code — fix the reported issues first, then re-run.
-- When calling markdown-formatter with action "check" or "lint", expect non-zero exit if the file has issues.
+# 2. markdown-formatter exit codes (200x observed — FIXED in t1345)
+#    Root cause was two bugs: (a) MCP tool exposed actions "lint","check","fix" but
+#    bash script only handled "format","advanced","cleanup" — unknown actions hit
+#    default case → exit 1; (b) fix_markdown_file() returned $changes_made (1 when
+#    changes were made) instead of 0, causing set -e to abort. Both fixed.
+#    MCP wrapper now captures output on non-zero exit instead of throwing.
+- markdown-formatter supports actions: format, fix, lint, check, advanced, cleanup.
+- If markdown-formatter still fails, check that .agents/scripts/markdown-formatter.sh exists and is executable.
 #
 # 3. read:file_not_found (53x observed)
 #    Root cause: assuming file paths from memory, AGENTS.md references, or prior