Linked environment address reproduction

AI-assisted; verified with the tests and tools listed above.

Requirements: repository dependencies installed with vp i, Node and Python 3.
Run the same driver against each checkout, sequentially:
  python3 driver.py --checkout <checkout> --output <new-run-directory> --side before
  python3 driver.py --checkout <checkout> --output <new-run-directory> --side after

The output directory must not exist. The driver starts two real T3 servers,
each with a fresh T3 home and linked-environments enabled. It never reads live
T3 state. Ports 19351 through 19354 must be free. It links the servers through
two HTTP proxies using the real CLI and pairing/OAuth flow, then makes the
first stored address accept requests without answering them.

When the driver writes the ready file, begin recording the terminal and create
an empty go file in that run directory. It performs t3_environment_links then
two forwarded t3_thread_list calls with allProjects: true through /mcp. The
peer has no projects or threads; both forwarded calls return successfully.
The terminal shows real wall-clock duration and request counters; no clock
manipulation or tests are involved. The driver terminates its own servers.

Captures: Ghostty terminal on an Xvfb 1280x800 display, font size 15, background
101820, foreground dce7ee, no decorations, cursor blinking disabled. ffmpeg
x11grab at 15 fps recorded the scripted calls. Final stills were captured twice
at least 500 ms apart and had identical SHA-256 hashes. Each video was reviewed
through one-second contact sheets, and each final still was visually inspected.

Base: fc2b5de20cb572d2333e03284466e3c804d25c84
Head: 4acc0b4edbb37dd626298cc6be6e0e63bc0a2ac4
Base listing: 0.040 s. Forwarded calls: 3.059 s, 3.044 s.
Head listing: 0.038 s. Forwarded calls: 0.104 s, 0.039 s.
Both: three probes and zero authenticated requests to the silent address;
four authenticated requests to the working address.

This is the loopback reproduction (3 s timeout). Non-loopback 10 s probes,
50-second forwarded wait chunks, and an address answering as a different peer
were not exercised. No web, desktop, or mobile UI claim is made.

Only sanitized terminal transcripts and measurements are published. Private
server startup logs and generated credentials are not public evidence.