PR evidence: Linux proc port scanning (#30011)

PR pingdotgg#30011: integrated client verification

Head: 83f14a2
Host: Linux arm64; real dev server/web client from the PR checkout; isolated worktree-local .t3 state. T3 built-in Browser panel.

The parent created two disposable HTML servers: one through the thread terminal (PID 2136240, port 34893) and one detached process group with the production T3CODE_THREAD_ID ownership tag (PID 2134886, port 41245). The latter is an agent-tagged fixture, not a paid provider run. Both appeared in this thread's Servers section, correctly labeled Terminal and Agent.

A project action configured http://localhost:34893/docs. A real client discoveredServers subscription using that configured URL returned the terminal fixture with the exact /docs path and configuredUrlProbing=true. The root URL and /docs both opened through the actual preview. Observations contain only fixture rows; other listeners were omitted.

The discovery subscription remained retained during the pass. Before stopping the fixture, server trace spans recorded 69 polling ticks, 75 scanSnapshot calls and 75 scanProcListeners calls. An isolated lsof shim on this dev process's PATH logged zero invocations. This is a functional integration observation, not an end-user timing benchmark. The separate child benchmark covers before/after performance and fallback.

The parent clicked Stop for only the owned agent fixture in Servers. Its PID exited and its entry disappeared; the terminal fixture still returned the expected HTML at /docs. The terminal fixture was then stopped with Ctrl+C in its own terminal. The dev server was left available for inspection. No live application state, real agents or unrelated processes were stopped. No source edits were needed; checkout stayed clean.

Screenshots: both-servers.png shows attribution; docs-preview.png shows the configured path in preview; after-stopping-agent.png shows only the terminal listener remains. observations.json records relevant actual client data; scan-counts.json records aggregate trace/shim counts. The fixture script and shim are included for reproduction.

Limits: native x64, macOS/Windows, desktop/mobile shells and remote/tunnel paths were not manually run. The service and wire contract are shared; no client/provider/contract changes were made. Existing first-holder inode-cache limitations and the rare fd-budget plus transient lsof failure limitation remain as described in the PR.

Created with GPT-6.1 Sol in Codex through T3 Code.