Clarify sandbox port-bind failures in browse startup#871
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tichenm wants to merge 3 commits intogarrytan:mainfrom
Open
Clarify sandbox port-bind failures in browse startup#871tichenm wants to merge 3 commits intogarrytan:mainfrom
tichenm wants to merge 3 commits intogarrytan:mainfrom
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added 3 commits
April 6, 2026 23:08
Sandboxed localhost binds can fail with EPERM or EACCES, but browse treated every bind error as either port contention or generic exhaustion. This extracts port probing into a dedicated helper, preserves explicit BROWSE_PORT handling, and surfaces permission-denied failures with actionable guidance instead of retrying into a misleading exhaustion message. Constraint: Some sandboxed environments reject 127.0.0.1 binds with EPERM/EACCES instead of EADDRINUSE Rejected: Keep the generic retry loop | misreports permission failures as port exhaustion Confidence: high Scope-risk: narrow Reversibility: clean Directive: Treat EPERM/EACCES as environment restrictions, not port contention, unless startup semantics are redesigned end-to-end Tested: bun test browse/test/findport.test.ts; bun test browse/test/; sandbox and escalated browse startup checks Not-tested: Non-sandbox environments that deny binds for reasons other than EPERM/EACCES
Browse now reports permission-denied bind failures clearly, but users upgrading from older installs can still encounter the legacy "No available port" message and misdiagnose it as port exhaustion. Add a troubleshooting note that distinguishes sandbox restrictions from real port contention and points users at rebuild or upgrade as the fix. Constraint: README troubleshooting needs to help both fresh installs and stale installs already in the field Rejected: Leave the explanation only in runtime error text | stale installs still surface the old misleading message Confidence: high Scope-risk: narrow Reversibility: clean Directive: Keep troubleshooting aligned with actual browse startup errors when startup diagnostics change Tested: README diff reviewed against current browse error strings Not-tested: Generated skill docs or website copies of this troubleshooting text
The port classification fix covers server startup directly, but the user-facing failure path usually goes through the CLI auto-start flow. Add a lifecycle regression test that boots the CLI with an explicit BROWSE_PORT and verifies the spawned server keeps that requested port in its state file. Constraint: The CLI startup path must stay testable without launching Chromium, so the regression uses BROWSE_HEADLESS_SKIP and a temporary state file Rejected: String-match the source for BROWSE_PORT forwarding | would miss real wiring regressions in the subprocess startup path Confidence: high Scope-risk: narrow Reversibility: clean Directive: Keep this test focused on preserved port wiring, not incidental status output formatting Tested: bun test browse/test/commands.test.ts -t "explicit BROWSE_PORT is preserved when CLI auto-starts the server"; bun test browse/test/findport.test.ts Not-tested: Full browse/test/ suite after adding this extra CLI lifecycle coverage
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Summary
BROWSE_PORThandling and add targeted regression coverageRoot cause
In sandboxed environments, binding
127.0.0.1:<port>can fail withEPERMorEACCES. Browse treated all bind failures as unavailable ports, retried 5 random ports, and then surfaced the misleading errorNo available port after 5 attempts.What changed
browse/src/port.tsEADDRINUSEas real contention, but surfaceEPERM/EACCESas environment restrictionsBROWSE_PORTthrough the same classification logicVerification
bun test browse/test/findport.test.tsbun test browse/test/Local port bind was blocked by the environment (EPERM)