fix: detect port conflicts on loopback addresses, not just 0.0.0.0

[gaojunran]

On macOS/BSD, Rust's TcpListener::bind sets SO_REUSEADDR by default, which allows binding 0.0.0.0:port to succeed even when 127.0.0.1:port (or ::1:port) is already occupied — because the kernel considers them different addresses. This caused check_ports_available() to report a port as available when it was actually in use on loopback, leading to daemons silently falling back to a different port while pitchfork still reported the original one.

Now check 0.0.0.0, 127.0.0.1, and ::1 for each candidate port so that a conflict on any loopback interface is detected reliably.

[gemini-code-assist]

Code Review

This pull request updates the port availability check in src/supervisor/lifecycle.rs to verify multiple addresses (0.0.0.0, 127.0.0.1, and ::1), addressing false negatives on platforms like macOS/BSD where SO_REUSEADDR is the default. Feedback was provided regarding the IPv6 check, which may incorrectly report a port conflict on systems where IPv6 is disabled; handling specific IO errors for the ::1 address was suggested to ensure compatibility across different environments.

[greptile-apps]

Greptile Summary

This PR fixes a false-negative in check_ports_available on macOS/BSD: because Rust sets SO_REUSEADDR by default, binding 0.0.0.0:port could succeed even when 127.0.0.1:port was already occupied, so the port appeared free. The fix probes all three addresses (0.0.0.0, 127.0.0.1, ::1) and only treats AddrInUse as a true conflict — other errors (e.g. EADDRNOTAVAIL on IPv6-disabled systems) are silently skipped, which also resolves the previously raised concern about IPv6-less environments.

Confidence Score: 5/5

Safe to merge — the fix is correct, well-scoped, and the previously raised P1 concern is already addressed in the current code.

No P0 or P1 findings remain. The prior thread's concern about Err(_) silently swallowing EADDRNOTAVAIL on IPv6-disabled hosts is resolved: the code now only treats AddrInUse as a conflict and skips all other errors. The three-address probe correctly covers the macOS/BSD SO_REUSEADDR edge case.

No files require special attention.

Important Files Changed

Filename	Overview
src/supervisor/lifecycle.rs	Expands check_ports_available to probe 0.0.0.0, 127.0.0.1, and ::1 and correctly treats non-AddrInUse errors (e.g. EADDRNOTAVAIL on IPv6-disabled hosts) as non-conflicts.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[check_ports_available called] --> B[For each candidate port]
    B --> C{port == 0?}
    C -- yes --> B
    C -- no --> D[spawn_blocking]
    D --> E[Try bind 0.0.0.0:port]
    E -- Ok --> F[drop listener]
    F --> G[Try bind 127.0.0.1:port]
    G -- Ok --> H[drop listener]
    H --> I[Try bind ::1:port]
    I -- Ok --> J[drop listener → return true]
    E -- AddrInUse --> K[return false]
    G -- AddrInUse --> K
    I -- AddrInUse --> K
    E -- Other error --> G
    G -- Other error --> I
    I -- Other error --> J
    K --> L[port_check = false]
    J --> M[port_check = true]
    L --> N[all_available = false, break]
    M --> O{all ports available?}
    O -- yes --> P[return resolved ports]
    O -- no --> Q{auto_bump?}
    Q -- yes --> R[increment bump_offset, retry]
    Q -- no --> S[return PortError]

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