MCP file upload for case input context

There is no pull request. The GitHub token for hammer-mt is invalid (gh auth status fails against github.com), so this could not be opened on EveryInc/checks. The reviewable change is upload-input.patch in this directory. It applies cleanly onto commit 18df437ab76efbc91c4c7796959be20c489049e9 (git apply --check succeeded against that tree).

git fetch origin 18df437ab76efbc91c4c7796959be20c489049e9
git checkout -b mcp-upload-input 18df437ab76efbc91c4c7796959be20c489049e9
git apply /path/to/upload-input.patch
bin/rails test test/models/case_inputs_test.rb test/integration/mcp_test.rb test/integration/upload_api_test.rb

The edited tree is also in code/.

What was missing

A case already stores the files a model starts with (Case has_many_attached :inputs). The bundle writes those paths beside prompt.md, and run.sh copies them into work/. Nothing in the MCP connection could attach them. add_task told the agent to ask the owner to upload inputs in the app, and the app has no input-upload form. The agent pasted source files into the prompt instead.

Assumption: "input context" means those case inputs, the workspace beside the brief, not eval/ fixtures or skill files. Eval files are what the checks read; run.sh never copies eval/, cases/, or skill/ into the workspace.

What to send the team

New MCP tool upload_input (18 tools on /mcp; the old README said 15 and was already missing create_benchmark and get_task).

The same path again replaces the file. The response lists every input on the case and an inputs_url. get_case and get_task now include that list, and the next bundle contains the bytes. The task page and the result page show the workspace path under Given files (a nested file is notes/slack-dm.md, not just slack-dm.md).

Files over 8 MB are refused by the tool with that inputs_url and nothing saved. The same bearer token can POST them as multipart to POST /benchmarks/:slug/tasks/:task/cases/:case/inputs with fields path and file. That route accepts up to 500 MB, the same ceiling as the importer. Owners and editors only; reviewers get the usual write refusal over MCP and 403 over HTTP.

Paths that would not survive into work/ are rejected and nothing is saved: absolute paths, .., prompt.md (that text belongs in the prompt), an instruction_override path, and anything under eval/, cases/, or skill/.

add_task and add_case now say to call upload_input instead of telling the owner to upload in the app. The server instructions and get_benchmark_context say the same thing, so an agent does not paste a Slack thread into the brief.

Tests

bin/rails test test/models/case_inputs_test.rb test/integration/mcp_test.rb test/integration/upload_api_test.rb — 19 runs, 174 assertions, 0 failures. That covers text and binary upload, replace-in-place, the bundle zip path (01-dashboard/cases/02-q3/notes/slack-dm.md), the task page link text, path rejection, a reviewer, the HTTP route, and the over-8 MB handoff to inputs_url.

The task page and result page label change was not opened in a browser. The task-page assertion is in McpTest.