Track upstream/browser-host localhost reachability gap

[fitchmultz]

Summary

External testing still reports open http://localhost:<port>/... and http://127.0.0.1:<port>/... failing with net::ERR_EMPTY_RESPONSE even when shell curl confirms the server is live.

Current wrapper state

The extension now documents and diagnoses this as browser-host loopback reachability:

• README Current limits notes that localhost resolves from the browser host, not necessarily the shell/Pi host.
• TOOL_CONTRACT documents the same boundary.
• Presentation adds a local fixture hint for loopback navigation failures.
• SUPPORT_MATRIX tracks RQ-0111 and RQ-0119.

Evidence

• Maintainer local direct probe with agent-browser 0.27.0 and a same-host Python HTTP server succeeds.
• External tester environment still fails with ERR_EMPTY_RESPONSE while shell curl succeeds.
• This suggests provider/browser launch namespace, proxy, container/VM, or host networking behavior outside this thin wrapper.

In-scope next action

Keep this issue as the local tracking link for upstream/environment follow-up. A true fix likely requires upstream agent-browser browser-launch networking support or an explicit host-bridge story. This extension should not add a server manager or localhost proxy without a separate design pass.

[fitchmultz]

Orchestrator triage on current main (b7cf5b3, released as 0.2.37): this is valid as an upstream/environment tracking issue, but the wrapper-owned work is already locally mitigated.

Evidence checked:

• docs/SUPPORT_MATRIX.md tracks RQ-0111 and RQ-0119: browser-host loopback reachability is environment/upstream-owned; same-host Python HTTP fixtures pass in maintainer local probes; the wrapper should not add a server manager or host bridge without a separate design pass.
• README.md, docs/TOOL_CONTRACT.md, and docs/COMMAND_REFERENCE.md document that localhost / 127.0.0.1 are resolved by the browser host, not necessarily the shell/Pi host.
• extensions/agent-browser/lib/results/presentation/errors.ts appends loopback navigation guidance for errors including net::ERR_EMPTY_RESPONSE.
• Regression coverage: test/agent-browser.presentation-skills-recovery.test.ts covers the local fixture hint, and npm run verify -- real-upstream passed against installed agent-browser 0.27.0 localhost fixtures today.

Fresh validation run:

• npm run verify ✅
• npm run verify -- real-upstream ✅
• Published package state: npm latest is pi-agent-browser-native@0.2.37, matching current release.

Status: blocked / upstream-boundary. Remaining work needs a minimal environment and direct upstream command set where shell curl reaches 127.0.0.1:<port> but direct agent-browser open http://127.0.0.1:<port>/... fails from the browser host. A true fix likely belongs in upstream browser launch/networking, proxy/namespace handling, or an explicit host-bridge story. No further local wrapper code change is justified without that evidence.

[fitchmultz]

Current status refresh (2026-06-25): still valid as an upstream/environment tracking issue; no local wrapper code change is justified right now.

Checked current state:

• Repo HEAD: 9f579a0; package/npm latest: pi-agent-browser-native@0.2.61.
• Target upstream baseline: agent-browser 0.30.1.
• Active docs still describe loopback as browser-host reachability, not shell/Pi-host reachability: README.md, docs/TOOL_CONTRACT.md, docs/COMMAND_REFERENCE.md.
• docs/support-notes.md keeps RQ-0111 / RQ-0119 classified as environment/upstream-owned and diagnostic-mitigated.
• Runtime presentation still appends local fixture guidance for loopback navigation failures in extensions/agent-browser/lib/results/presentation/errors.ts, with coverage in test/agent-browser.presentation-skills-recovery.test.ts.

Status remains: blocked / upstream-boundary / needs-repro. Next useful evidence is still a minimal environment plus direct upstream command set where shell curl reaches 127.0.0.1:<port> but direct agent-browser open http://127.0.0.1:<port>/... fails from the browser host. No server manager or host bridge should be added without a separate design pass.