Plugin command API shim (#26564)

packages/opencode/specs/v2/tui-command-shim.md

@@ -0,0 +1,67 @@
+# TUI Command Shim Removal
+
+Problem:
+
+- v1 keeps a deprecated `api.command` TUI plugin shim so older plugins do not fail during initialization
+- v2 should expose only the keymap command API
+- tests and fixtures should not encode legacy command behavior as expected behavior
+
+## Remove Public Types
+
+In `packages/plugin/src/tui.ts`, remove:
+
+- `TuiCommand`
+- `TuiCommandApi`
+- `TuiPluginApi.command`
+
+Keep `api.keymap` as the only TUI command registration and execution surface.
+
+## Remove Runtime Shim
+
+Delete `packages/opencode/src/cli/cmd/tui/plugin/command-shim.ts`.
+
+In `packages/opencode/src/cli/cmd/tui/plugin/api.tsx`, remove:
+
+- the `createCommandShim` import
+- the `command: createCommandShim(...)` field from `createTuiApi(...)`
+
+In `packages/opencode/src/cli/cmd/tui/plugin/runtime.ts`, remove:
+
+- the `createCommandShim` import
+- the `command: createCommandShim(...)` field from `pluginApi(...)`
+
+## Migration Target
+
+Plugin authors should replace old calls with keymap calls:
+
+```ts
+api.keymap.registerLayer({
+  commands: [
+    {
+      name: "plugin.command",
+      title: "Plugin Command",
+      namespace: "palette",
+      slashName: "plugin",
+      run() {
+        api.ui.dialog.clear()
+      },
+    },
+  ],
+  bindings: [{ key: "ctrl+shift+p", cmd: "plugin.command" }],
+})
+```
+
+Direct replacements:
+
+- `api.command.register(cb)` -> `api.keymap.registerLayer({ commands, bindings })`
+- `api.command.trigger(name)` -> `api.keymap.dispatchCommand(name)`
+- `api.command.show()` -> `api.keymap.dispatchCommand("command.palette.show")`
+- `onSelect(dialog)` -> use `api.ui.dialog` from the plugin API closure
+
+## Verification
+
+After removal, run from package directories:
+
+- `bun typecheck` in `packages/plugin`
+- `bun typecheck` in `packages/opencode`
+- TUI plugin loader tests in `packages/opencode` if runtime plugin API wiring changed