[raiseCatError]

Stacked on #516 (Kitty native shaders), so this diff is Slice 3 only. Retarget after #516 lands, and only after review.

What

/appearance › Ghostty shaders: NMSh-original GLSL passes for Ghostty, composed after the person's own shaders.

• Version gates verified against Ghostty's shader prefixes for 1.2.0, 1.3.0, 1.3.1 and 1.4.0. The 1.3.x and 1.4.0 prefixes are identical. Each preset needs only the uniforms it reads.
  • Fail closed (nothing offered): no reported version (tmux, ssh), anything older than 1.2, or anything newer than 1.4.x.
• Presets (one trail at a time): Smear, Comet, Aurora, Dim when unfocused, Vignette, Scanlines, Text glow.
  • Every parameter is compiled in, and a test proves it changes the source.
  • Values are validated, never clamped.
• Composition: one optional config-file = ?… include at the end of the effective root config.
  • A simulation of Ghostty's config graph must show the person's passes unchanged and in order, or the plan is refused.
  • It models: roots, the include queue, clears, ?, quotes, and relative paths.
  • NMSh never writes custom-shader = resets or custom-shader-animation.
• Ownership: ledger plus the Slice 1 snapshot transaction.
  • Exact review before any write; re-planned at confirm.
  • Exact removal, including CRLF and no-final-newline files.
  • Edited or unowned files are preserved.
  • The launch command line is checked for config/shader overrides.
• Never two trails:
  • Refuses a trail next to the person's cursor shader, or next to a shader it cannot read.
  • Pauses NMSh's older /cursor Ghostty shader inside the same transaction; removal resumes it the same way.
  • A reload-pending record keeps Portable from drawing over a trail Ghostty may still have loaded.
• Gates: Reduced Motion, Effects Off, the Portable renderer and non-trail motion all remove NMSh passes on sync, including once at startup. Inside tmux, the version recorded at review is used.
• Architecture: TerminalApp stays host-neutral, with all wiring in glslStudio.ts. Kitty and Ghostty share one ShaderStudioPanel.

Verification

• Canonical npm run verify on frozen source: 4662 tests, 4648 pass, 0 fail, 13 skipped, 1 existing todo; exit 0.
• Focused 132/132.
• Live tests on installed Ghostty 1.3.1 and on a staged, signature-verified 1.4.0, both headless with a private HOME:
  • the uniform table matches each binary;
  • +validate-config accepts NMSh's composed config;
  • a slangc proxy compile accepts every preset.
• An independent review (Codex, read-only) found no blocker. All 7 of its findings were fixed with regression tests.

Not verified: GPU rendering and physical Ghostty/Kitty/Zed QA were not run. The compile is a proxy: Ghostty's glslang → SPIRV-Cross → Metal path was not exercised.

#516's Mermaid CI failure (run 40656373289) is unrelated and is not touched here. It was not rerun. Local runs pass 3/3; see the diagnosis in the docs.