fix(tui): empty states, context, and minor improvements to diff viewer (#28878)

packages/opencode/src/server/routes/instance/httpapi/groups/instance.ts

@@ -26,6 +26,7 @@ const PathInfo = Schema.Struct({
 export const VcsDiffQuery = Schema.Struct({
   ...WorkspaceRoutingQueryFields,
   mode: Vcs.Mode,
+  context: Schema.optional(Schema.NumberFromString.check(Schema.isInt(), Schema.isGreaterThanOrEqualTo(0))),
 })
 
 export class ApiVcsApplyError extends Schema.ErrorClass<ApiVcsApplyError>("VcsApplyError")(

packages/opencode/src/server/routes/instance/httpapi/handlers/instance.ts

@@ -48,8 +48,10 @@ export const instanceHandlers = HttpApiBuilder.group(InstanceHttpApi, "instance"
       return yield* vcs.status()
     })
 
-    const getVcsDiff = Effect.fn("InstanceHttpApi.vcsDiff")(function* (ctx: { query: { mode: Vcs.Mode } }) {
-      return yield* vcs.diff(ctx.query.mode)
+    const getVcsDiff = Effect.fn("InstanceHttpApi.vcsDiff")(function* (ctx: {
+      query: { mode: Vcs.Mode; context?: number }
+    }) {
+      return yield* vcs.diff(ctx.query.mode, { context: ctx.query.context })
     })
 
     const getVcsDiffRaw = Effect.fn("InstanceHttpApi.vcsDiffRaw")(function* () {

packages/opencode/src/server/routes/instance/httpapi/public.ts

@@ -66,6 +66,7 @@ const QueryParameterSchemas: Record<string, OpenApiSchema> = {
   "GET /session roots": QueryBooleanOpenApi,
   "GET /session limit": { type: "number" },
   "GET /session/{sessionID}/message limit": { type: "integer", minimum: 0, maximum: Number.MAX_SAFE_INTEGER },
+  "GET /vcs/diff context": { type: "integer", minimum: 0 },
   "GET /api/session limit": { type: "number" },
   "GET /api/session start": { type: "number" },
   "GET /api/session roots": QueryBooleanOpenApi,