[dex0shubham]

The bug

relocateOpenAIPins moves a pin: it appends the tail <system-reminder> block and removes the command line from where the user typed it. pin.ts states that contract in three places, e.g.

A mixed turn keeps its prose and loses only the command lines, so the model is not distracted by configuration in the middle of a request it has to act on.

It strips instructions and every system/developer/user entry of items — but items is undefined when /v1/responses is called with a bare string input, a shape the function explicitly supports (normalizeOpenAIRequest wraps it as a user turn). That branch only appended:

if (stringInput) {
  req.input = `${req.input as string}\n\n${pinText}`;   // no strip
}

For input: 'explain this function\n@pxpipe pin be concise, no walls of text':

shape	prose after relocation
string input	explain this function\n@pxpipe pin be concise, no walls of text + the block
array input	explain this function + the block
messages	explain this function + the block

Why it reaches upstream

transformOpenAIResponses captures the relocated string as originalInputString after relocateOpenAIPins runs and wraps it back into req.input verbatim when it rebuilds the user item, so nothing downstream removes it. It also survives the bail path, which returns pinBody. The model is handed the configuration line as part of the request it has to answer — precisely what the MOVE contract exists to prevent — and a pin is copied rather than moved on one of the three wire shapes.

Only mixed turns are affected: a command-only turn is answered locally by pinCommandResponseOpenAI in proxy.ts before any transform runs.

The fix

Strip at the same call site, mirroring stripOpenAIContent on the array path. The empty-remainder branch keeps the request valid if a command-only body is ever reached by another route; given the local short-circuit it is belt-and-braces, not a live path. Happy to drop it if you prefer the narrower one-liner.

Tests

The OpenAI relocation path had no tests, so tests/pin-openai-relocate.test.ts is new: 6 cases covering all three input shapes, instructions + string input together, a no-pin request left untouched, and an assistant turn quoting the syntax (foldPins reads user turns only, so stripping it would edit the model's own words out of history).

Against the unfixed pin.ts exactly the 2 string-input cases fail and the 4 controls pass unchanged. Full suite: 86 files / 1299 tests green, tsc --noEmit clean.