PR 29006 real dev verification, 2026-11-02, Linux VM

Baseline: github/main cc59f99e735300120a6fc74d9a0b9df7c98fa81c
PR head: a981ba08af2bd7068476335357ec36274444ff22

$ git worktree add ../main github/main
$ cd ../main && vp i
$ setsid nohup timeout 7000 vp run dev > /tmp/main-dev.log 2>&1 &
Main used T3CODE_DEV_SEED=0 and isolated /home/user/main/.t3.
[dev-runner] serverPort=16733 webPort=8693

Browser: repo Playwright 1.60.0, /usr/bin/google-chrome, 1440x1000.
Added /home/user/icon-verification through Add project > Local folder.
Selected Codex gpt-6.1-sol and submitted a real turn through the composer.
Provider created and committed real PNGs using Node crypto and zlib:
favicon.png / oversized.png: 5,763,023 bytes, 1600x1200 RGB
small.png: 95 bytes, 32x32 solid green

Chrome CDP measured actual app requests to the running server.
No request bodies, response bodies, or app fetch functions were replaced.
At request stage, icon requests were continued after applying Chrome network
emulation at 524,288 download bytes/s, 50 ms latency. Other app loading was
unthrottled before these requests. Both runs used disabled browser HTTP cache.

main, content-length=5763023:
  Fetch / favicon.png: loadingFinished; body bytes=5763023; duration=22255 ms
  Image / favicon.png: loadingFinished; body bytes=5763023; duration=22193 ms
The rejected cache Fetch continued downloading the entire oversized body.

Stopped main using its captured launch PID/process group before starting PR.
Copied only this task-owned development state into the PR isolated .t3 home.

$ git switch --detach a981ba08af2bd7068476335357ec36274444ff22
$ vp i
$ setsid nohup timeout 6000 vp run dev --home-dir /home/user/t3code/.t3 --no-seed > /tmp/dev.log 2>&1 &
[dev-runner] serverPort=13773 webPort=5733

PR, same PNG and Chrome conditions, content-length=5763023:
  Fetch / favicon.png: loadingFailed; canceled=true; net::ERR_ABORTED;
                      body bytes=0; duration=342 ms
  Image / favicon.png: loadingFinished; body bytes=5763023; duration=11149 ms
The changed cache Fetch cancels. The separate existing image fallback still
loads and renders the original PNG; this PR does not prevent that download.
CDP byte counts describe body bytes delivered to the browser, not server-side
socket buffering. Durations are observations of these runs, not a benchmark.

Neighbor checks through project settings:
  Choose file > small.png: green 32x32 icon renders as data:image/png.
  Reset project icon to default: Automatic restores the oversized PNG.
  Choose small.png again: green icon returns.
  Reload: green 32x32 data URL remains; zero small.png network requests.

Fresh real Codex gpt-6.1-sol turn on PR, submitted through composer:
  favicon.png: 5,763,023 bytes, 1600 x 1200 png
  oversized.png: 5,763,023 bytes, 1600 x 1200 png
  small.png: 95 bytes, 32 x 32 png
  git status --short: no output
  ICON_VERIFICATION_OK
The turn completed in the client; no files modified.

$ blacksmith-check run --id <task-owned-worker> "vp i && vp test run packages/client-runtime/src/projectFaviconCache.test.ts"
  Test Files 1 passed (1)
  Tests 8 passed (8)
  Worker stopped after completion.
Existing GitHub CI on this exact PR head was green.

Not exercised: native mobile, Electron shell, macOS/Windows, tunnel/relay links.
No production source modifications, commits, pushes, labels, or merge actions.