fix(mcp): keep available_projects error JSON valid when many projects (#235)#735
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…#235) collect_db_project_names built the "project not found or not indexed" error's available_projects list into a fixed 4 KB buffer and, on overflow, let snprintf truncate the last name mid-token then clamped offset to the buffer end -- so the error response was malformed, unterminated JSON (e.g. ...,"tmp-cb],"count":50}) whenever enough projects were indexed to overflow the buffer. A client parsing the error would fail. Found while exercising the CLI against a cache with 280 indexed projects. Write element-boundary instead: before each name, require the whole element (optional leading comma + the quoted name + NUL) to fit in the remaining buffer; otherwise stop at that boundary. The array then always holds only complete names and count == its length, so the JSON is always valid (just fewer names when the buffer is full -- callers can run list_projects for the complete set). Reproduce-first: tool_bad_project_error_valid_json_issue235 builds 50 dbs with ~120-char internal names (well over 4 KB), triggers the error, and asserts the response parses as JSON and available_projects is an array with length == count. RED before (yyjson_read returns NULL on the truncated buffer), GREEN after. The existing tool_bad_project_name_no_overflow_issue235 (buffer bounds) still passes. Full suite 5736/0. Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>
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Malformed-JSON bug in the "project not found" error, found while exercising the new CLI flags against a cache with 280 indexed projects.
Bug:
collect_db_project_namesbuilds the error'savailable_projectslist into a fixed 4 KB buffer. On overflow,snprintftruncated the last name mid-token and the code clampedoffsetto the buffer end — so the error response was unterminated, invalid JSON (…,"tmp-cb],"count":50}) once enough projects were indexed to overflow the buffer. A client parsing the error would fail.Fix: write element-boundary — before each name, require the whole element (optional leading comma + quoted name + NUL) to fit; otherwise stop at that boundary. The array then always holds complete names and
count== its length → always valid JSON (just fewer names when full; the hint already points callers tolist_projectsfor the full set).Reproduce-first:
tool_bad_project_error_valid_json_issue235— 50 dbs with ~120-char internal names (well over 4 KB), triggers the error, asserts the response parses as JSON andavailable_projectsis an array withlength == count. RED before (yyjson_read→ NULL on the truncated buffer), GREEN after. The existingtool_bad_project_name_no_overflow_issue235(buffer-bounds guard) still passes. Full suite 5736 / 0.Follow-up from the CLI-reliability series (#640/#680/#704/#719).