fix: preserve prompt-cache prefix for side conversation forks - #4543
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Move the side-conversation boundary from the system prompt into the first fork-owned user turn and route OpenAI promptCacheKey through the parent session id so fork requests share the parent prefix. Fixes apache#4540 Generated-by: Cursor
Move the side-conversation boundary from the system prompt into the first fork-owned user turn, route OpenAI promptCacheKey through the parent session id, and add a runtime-host regression test that compares parent and fork provider request bodies. Fixes apache#4540 Generated-by: Cursor
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- Keep lazy fork-on-first-send behavior from main - Preserve prompt-cache boundary wording from apache#4543 Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
Side conversation forks injected the boundary into the system prompt, which
changed the prompt-cache prefix relative to the parent session. This moves the
boundary onto the first fork-owned user turn and routes OpenAI
promptCacheKeythrough the parent session id so inherited tools/system/history stay aligned.
Fixes #4540
Verification
npm run lintnpm run format:checknpm --workspace @maka/core run build && npm --workspace @maka/core run test:distnpm --workspace @maka/runtime run buildnpm --workspace @maka/runtime-host run buildnpm --workspace @maka/runtime-host run test:dist(includes side-conversation prompt-cache regression)npm run typecheck(root still fails on unrelated@maka/desktopupstream errors)AI use
Tool(s) and scope: Cursor — implementation, unit tests, and runtime-host regression test.
Checklist
Does this PR entail a change in behavior?