PR #27391 runtime verification, Linux x64, Chrome 151, real dev server
main: 6575ce3250; PR: 131dfbc2cca78ecbda61f84bebeeafcf18d32341
Installed both checkouts with vp i. Created a real repo project and threads via web UI.
No mocks, fixture data, host-platform override, or source edits.

Real UI: Settings > Providers > Add provider > Show more > ACP Registry.
Both builds: 35 compatible agents; query gemini => Gemini CLI.
PR: no-such-agent-pr27391 => no compatible agents; clear => 35; gemini => Gemini CLI.

Main server PID/TID 31236. strace during actual registry search:
31236 14:55:24.094561 statx(AT_FDCWD, "/home/user/.local/bin/npm", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7ffdf4da03a0) = -1 ENOENT (No such file or directory)
31236 14:55:24.094632 statx(AT_FDCWD, "/home/user/.npm-global/bin/npm", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7ffdf4da03a0) = -1 ENOENT (No such file or directory)
31236 14:55:24.094664 statx(AT_FDCWD, "/home/user/.bun/bin/npm", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7ffdf4da03a0) = -1 ENOENT (No such file or directory)
31236 14:55:24.095522 access("/home/user/.nvm/versions/node/v24.22.1/bin/npm", X_OK) = 0
31236 14:55:24.096273 access("/home/user/.nvm/versions/node/v24.22.1/bin/npm", X_OK) = 0

PR server main PID/TID 37819. Same UI search; filesystem probes on worker TIDs:
37882 14:59:44.767997 statx(AT_FDCWD, "/home/user/.local/bin/npm", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7693c91c7ab0) = -1 ENOENT (No such file or directory)
37883 14:59:44.768665 statx(AT_FDCWD, "/home/user/.npm-global/bin/npm", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7693c89c6ab0) = -1 ENOENT (No such file or directory)
37885 14:59:44.769110 statx(AT_FDCWD, "/home/user/.bun/bin/npm", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7691b37fdab0) = -1 ENOENT (No such file or directory)
37884 14:59:44.769344 statx(AT_FDCWD, "/usr/local/cargo/bin/npm", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7691b3ffeab0) = -1 ENOENT (No such file or directory)
37885 14:59:44.778417 access("/home/user/.nvm/versions/node/v24.22.1/bin/npm", X_OK) = 0

This proves the synchronous-versus-asynchronous resolver mechanism on Linux.
It does NOT reproduce Windows UI latency or establish a performance measurement.

Real provider turns, started in web composer, Codex gpt-6.1-sol:
main:
{"method":"item/completed","command":"/bin/bash -lc 'pwd && git rev-parse --show-toplevel'","cwd":"/home/user/t3code","output":"/home/user/t3code\n/home/user/t3code\n","exitCode":0}
{"method":"item/completed","text":"codex launch verified."}
{"method":"turn/completed","status":"completed","error":null}
PR:
{"method":"item/completed","command":"/bin/bash -lc 'pwd && git rev-parse --show-toplevel'","cwd":"/home/user/t3code","output":"/home/user/t3code\n/home/user/t3code\n","exitCode":0}
{"method":"item/completed","text":"codex launch verified."}
{"method":"turn/completed","status":"completed","error":null}
Provider command and final reply exist in protocol logs. Neither initial live view displayed the reply. Reloading the PR thread displayed the persisted final reply: codex launch verified. Live rendering is a baseline limitation observed on both builds, not attributed to this PR.

PR real package preparation: clicked Add Gemini CLI; wizard advanced to identity.
{"agentId":"gemini","agentVersion":"0.66.0","distribution":"npx","packageSpec":"@google/gemini-cli@0.66.0","managerPath":"/home/user/.nvm/versions/node/v24.22.1/bin/npm","binDirectory":"/home/user/t3code/.t3/tools/gemini/0.66.0/npm/bin","executablePath":"/home/user/t3code/.t3/tools/gemini/0.66.0/npm/bin/gemini","packageRoot":"/home/user/t3code/.t3/tools/gemini/0.66.0/npm/lib/node_modules/@google/gemini-cli","packageVersion":"0.66.0"}

No Gemini sign-in or turn attempted.

Focused existing tests via blacksmith-check: 4 files, 92 passed, 2 existing Windows-only skips.
CI head 131dfbc: 30 successful, 0 pending, 0 failing.
Unverified: native Windows PATH/PATHEXT, cmd/bat launcher quoting, macOS Git/Xcode selection, native clients, authenticated Claude/Muse turns.