tracker: add windows support

[wey-gu]

Windows support — status tracker

Rolling tracker for the Windows port. Live design plan: docs/impl/windows-port.md. Related Linux tracker: #18.

TL;DR

• First Windows beta shipped as v0.1.0-beta.25; current Windows support is no longer a placeholder or bring-up track.
• The core backend is landed: ConPTY + shared libghostty-vt, D3D11/DirectWrite glyph-atlas renderer, GPUI-hosted offscreen image bridge, input, mouse, clipboard, custom titlebar, DPI, resize, and Windows distribution v0.
• PR win: harden terminal paths, fullscreen redraws, and input latency #64 fixed the Windows reserved CON path/config issue (windows os save fail #56), fullscreen/maximize bottom-row rendering, and the first large typing-latency pass.
• PR perf: reduce non-macOS terminal command latency #68 closed the deeper command-output latency pass behind bug(win): performance issue #57: preserved ConPTY output wake cadence, removed speculative keydown repaints, switched PTY readbacks to mailbox semantics, added exact dirty-row readback, corrected translucent row replacement, and followed Windows Terminal default shell profile selection where possible.
• User-side testing before merge confirmed materially improved Windows command-output latency. bug(win): performance issue #57 is closed as addressed by win: harden terminal paths, fullscreen redraws, and input latency #64 + perf: reduce non-macOS terminal command latency #68.
• The remaining structural renderer gap is direct DirectComposition / swap-chain presentation inside GPUI so the temporary GPU -> CPU -> GPUI image bridge can be removed entirely.
• CJK IME commit/preedit input landed in PR [codex] Add Windows and Linux CJK IME input #99 and was user-smoke-tested on Windows. Remaining polish is now hardening and distribution: IME edge-case/international-keyboard validation, advanced selection, shell integration, ligatures, extreme resize/multi-monitor/GPU cases, code signing, installer/signing strategy, and updater hardening.
• PR Fix:Linux WSL illegal-instruction startup && inline LaTex #100 hardened the shared non-macOS libghostty-vt build by deriving an explicit generic Zig target from Cargo's target triple. This mainly fixed the Linux/WSL illegal-instruction report in crash on WSL ubuntu 22.04.5 #97, but it also improves Windows artifact reproducibility by preventing accidental native-host CPU feature leakage.

Done

Phase 0 — workspace + portable CI

• Cross-platform workspace and cfg gates.
• Portable crates compile on Windows.
• Windows named-pipe control socket (\\.\pipe\con).
• Feature-gated Windows binary name con-app.exe because CON is a reserved DOS device name.
• .cargo/config.toml aliases (wbuild, wrun, wtest) for the Windows feature set.
• Portable CI includes Windows checks.

Phase 1/2 — backend foundation

• ConPTY spawn, resize, reader/writer pipes, lifecycle, and teardown.
• Shared libghostty-vt integration through Zig; current validated Zig line is 0.15.2.
• Generic non-macOS libghostty-vt Zig target selection landed in PR Fix:Linux WSL illegal-instruction startup && inline LaTex #100 so Windows VT artifacts are not tied to the build machine's native CPU feature set.
• Windows facade types exposed through the same GhosttyApp / GhosttyTerminal shape used by the app.

Phase 3a/3b — renderer and terminal grid

• D3D11/DirectWrite renderer with runtime-compiled HLSL pipeline.
• D3D11 instanced grid draw path.
• Skyline-packed BGRA glyph atlas.
• IoskeleyMono bundled font resolution and DirectWrite fallback.
• Nerd-Font / PUA rasterization, atlas bleed fix, wide-glyph z-order, inverse cursor, bold/italic/underline/strikethrough, palette fallback.
• Offscreen RenderSession bridge into GPUI image rendering; no child HWND dependency in the current path.

Phase 3c — input, selection, shell interaction baseline

• Keyboard routing through GPUI focus.
• xterm-style key encoding for function keys, arrows, Home/End/PgUp/PgDn, Insert/Delete, Shift+Tab, Alt-meta, Ctrl-letter.
• DECCKM and bracketed paste.
• SGR mouse reports, wheel forwarding, selection rendering, Shift-bypass for app mouse tracking.
• Win32 clipboard.
• Pane focus and titlebar/caption button behavior.
• Fullscreen/maximize bottom-row correctness after the Neovim repro from the beta cycle.
• CJK IME commit/preedit input via GPUI InputHandler, with cursor-relative candidate bounds and width-aware CJK/wide preedit positioning. Landed in PR [codex] Add Windows and Linux CJK IME input #99.

Phase 3e — latency work landed in #64 + #68

• Wake GPUI from the ConPTY reader thread.
• Generate terminal images in the render path so fresh output can land in the current frame.
• Reduce hot-path work: blank-cell skip, zero-fill removal, conditional wide-glyph sort.
• Keep low-latency presents armed until VT generation actually advances.
• Preserve successive output wakes instead of draining bursty command output into one repaint.
• Treat the staging ring as a mailbox for PTY-driven output.
• Avoid presenting stale completed readbacks ahead of fresher submitted snapshots.
• Derive exact dirty rows and use D3D row-region readback for small updates.
• Replace dirty rows inside a CPU BGRA backing frame before publishing the GPUI image, preserving translucent terminal semantics.
• Keep command-start output latency-critical long enough for delayed shell output.
• Follow Windows Terminal default profile selection where possible; CON_SHELL remains explicit override.
• Add CON_GHOSTTY_PROFILE / CON_LOG_FILE instrumentation for ConPTY, VT snapshot, renderer, render session, and GPUI image handoff timings.

Phase 5 v0 — beta distribution

• Windows release workflow creates ZIP + SHA256 sums.
• PowerShell one-line installer path exists.
• Appcast/update metadata exists.
• Settings update card and command-palette check action exist.
• Release channel/version are baked from tags.
• In-place update path exists for the beta installer flow.

Remaining work

Structural performance

• Direct presentation inside GPUI: land or obtain a GPUI API for an external DirectComposition/swap-chain surface, then remove the D3D readback + RenderImage re-upload bridge.
• Re-profile with PIX / GPUView / ETW after direct presentation exists; current instrumentation is sufficient for the existing bridge but not a substitute for GPU timeline validation.

Terminal hardening

• IME/dead-key/international-keyboard validation matrix across Windows IMEs and keyboard layouts.
• Double-click word selection, triple-click line selection, drag-to-scroll selection, Alt-drag column selection.
• Ctrl+Space -> NUL behavior where text events are ambiguous.
• OSC 133 / OSC 7 shell integration parity.
• Ligatures and remaining font-shaping polish.
• Extreme resize, high-DPI, multi-monitor, and multi-GPU edge cases.

Distribution hardening

• Code signing so SmartScreen trust improves.
• Signature verification for downloaded update artifacts.
• Decide final installer format: MSI/MSIX/cargo-dist/winget in addition to the current ZIP + PowerShell installer.
• ARM64 strategy.

Upstream / GPUI follow-ups

• External swap-chain / DirectComposition attachment API for GPUI Windows.
• Optional GPUI close-race log cleanup for benign window not found / invalid-handle noise on teardown.

References

• Plan: docs/impl/windows-port.md
• Latency postmortems: postmortem/2026-04-26-windows-row-readback-upload-latency.md, postmortem/2026-04-26-windows-command-render-latency.md
• Renderer postmortem: postmortem/2026-04-21-windows-atlas-pua-rasterization.md
• Close-noise postmortem: postmortem/2026-04-21-windows-x-close-log-noise.md
• Related fixed issues: windows os save fail #56, bug(win): performance issue #57, feat(windows): CJK IME input #89
• Related PRs: win: harden terminal paths, fullscreen redraws, and input latency #64, perf: reduce non-macOS terminal command latency #68, [codex] Add Windows and Linux CJK IME input #99, Fix:Linux WSL illegal-instruction startup && inline LaTex #100

[wey-gu]

Windows v0 shipped — v0.1.0-beta.25

The Windows port crossed from "in preparation" to "first beta" today. Release pipeline is building now: https://github.com/nowledge-co/con/actions

What's in v0:

• con-app.exe runs standalone (unzip and go; no installer).
• ConPTY + libghostty-vt terminal backend.
• D3D11/DirectWrite renderer: glyph atlas (PUA three-case rasterization), grid draw, cursor, selection, DPI, Mica backdrop.
• Full keyboard (F1-F12, modifier-aware arrows, Alt-meta, Shift+Tab, …) and mouse (SGR-1006 report, Shift-bypasses-tracking, selection extend).
• Win32 clipboard (Ctrl+Shift+C/V), bracketed paste, DECCKM.
• Titlebar drag region + Min/Max/Close caption buttons (theme-aware, white-on-red only on close hover).
• Embedded app icon (via winresource).
• Notify-only update checker: polls the Sparkle appcast, surfaces a download link in Settings → Updates. No exe self-replace yet.
• Re-enabled Windows CI in ci-portable.yml (clones outside the reserved D:\a\con\con path to C:\src\repo).
• Release pipeline (release-windows.yml) produces a ZIP + SHA256SUMS + Sparkle-signed appcast on every v* tag.

Distribution caveats (v0):

• Unsigned: SmartScreen prompts on first launch. Code-signing is Phase 5.
• Portable ZIP, not installer: no registry writes, no Start Menu entry.
• Notify-only update: user downloads the new ZIP manually. Full self-update is a follow-up.

Still open:

• Phase 3c tail — double/triple-click word/line select, drag-to-scroll past pane edges, Alt+drag column select, OSC 133 shell integration, IME.
• Phase 4 hardening — CJK IME, extreme-size resize, ligatures.
• Phase 5 distribution — code signing, MSIX/installer, full auto-update.
• Upstream GPUI PRs (unchanged from prior status): external-swapchain handle + window-teardown race / "window not found" log noise.

Plan doc: docs/impl/windows-port.md. Keeping this tracker open for Phase 3c tail + Phase 4/5.

[wey-gu]

Merged update for PR #64 (win: harden terminal paths, fullscreen redraws, and input latency).

What landed:

• Windows reserved-path fix via con-paths so config/data/auth/theme/skills no longer hit reserved CON path failures (windows os save fail #56)
• Zig cache hardening so the Windows Ghostty build picks a short writable cache path before falling back into Zig/uucode spawn failures
• fullscreen/maximize correctness fixes in alt-screen apps like Neovim:
  • full VT redraw after resize/full invalidation
  • trailing-row cleanup on full redraw
  • async resize geometry alignment with Ghostty render-state rows/cols
  • stable wrapper bounds for pane sizing
  • resize redraws kept off the blocking path to avoid maximize hangs
• Windows renderer latency work:
  • same-frame terminal image generation in the GPUI render path
  • VT-generation-aware low-latency presents
  • typing-burst low-latency arming
  • mailbox staging-ring behavior with clean-slot preference
  • geometry fingerprint fix so async resize catch-up frames are not skipped
  • hot-path reductions (blank-cell skip, zero-fill removal, conditional wide-glyph sort)

User-visible outcome from the merge cycle:

• the Windows terminal now feels materially faster during interactive typing
• maximize/fullscreen no longer hangs the app in the reproduced Neovim case
• the hidden bottom command row issue after zoom/maximize is fixed

Tracker status after this merge:

• windows os save fail #56 should be considered addressed by the merged path fix
• bug(win): performance issue #57 should be considered materially advanced by the merged renderer latency work, though the deeper structural gap remains until direct compositor presentation lands
• the remaining big Windows performance item is still Phase 3d / Phase 3e: eliminate the GPU -> CPU -> GPU readback path by presenting directly into GPUI's composition tree

Remaining Windows work worth tracking here:

• direct presentation path (Phase 3d / 3e)
• IME and hardening polish
• code signing / distribution hardening