47 lines
2.1 KiB
Markdown
47 lines
2.1 KiB
Markdown
 
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# mdt console — SIGWINCH Self-Pipe Pattern (coral.googlesource.com)
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## Metadata
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| Field | Value |
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| Institute | Molodetz Institute — Research & Retrieval Division |
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| Subject | shell-multiplexer-auto-attach |
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| Document type | Source Dossier |
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| Tier | 1 |
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| Source title | console: Add in SIGWINCH support |
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| Source URL | https://coral.googlesource.com/mdt/+/d5b37aa3c97daf3e29b0aeacfce1c5d3beb1dff8%5E%21/ |
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| Source publisher / author | Google Coral (mdt project) |
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| Source type | repository |
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| Source date (published) | Unknown — not stated |
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| Date researched | 2026-10-09 |
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| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
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| Research method | web search synthesis |
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| Confidence | Medium |
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| Status | Active |
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## Summary
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A commit adding SIGWINCH support to Google's `mdt` console tool, using the standard "signal handler just sets a flag (or writes to a self-pipe); the real work happens in the main loop" pattern — the handler itself never calls the ioctl or touches shared state directly.
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## Key findings
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- Signal handlers should do the absolute minimum (set a flag / write one byte to a self-pipe) because most libc/syscall operations are not safe to call from inside a signal handler; the actual `TIOCGWINSZ` read and any forwarding happens back in the normal event loop once it notices the flag/pipe-byte.
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## Pros / strengths
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- A real, shipped example of the "minimal signal handler, defer the work" discipline applied specifically to SIGWINCH, in Python-adjacent/C-level console tooling from a credible engineering org.
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## Cons / limitations / caveats
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- Specific to `mdt`'s own event-loop shape; the general principle (minimal handler, deferred work) transfers, the exact code structure doesn't.
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## Relevance to tai
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If tai ever writes its own `SIGWINCH` handler (e.g. in a thin Python control process around tmux), it must follow this exact discipline — `signal.signal(signal.SIGWINCH, lambda *a: flag.set())` and do the real `ioctl`/forwarding work in the main loop, never inside the handler itself.
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## Changelog
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| Date | Change |
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| 2026-10-09 | Initial dossier created. |
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