refactor(opencode): simplify tool output disable config

packages/opencode/src/config/config.ts

@@ -49,13 +49,7 @@ const log = Log.create({ service: "config" })
 // Custom merge function that concatenates array fields instead of replacing them
 // Keep remeda's deep conditional merge type out of hot config-loading paths; TS profiling showed it dominates here.
 function mergeConfig(target: Info, source: Info): Info {
-  const merged = mergeDeep(target, source) as Info
-  if (!target.tool_output || !source.tool_output) return merged
-  if (target.tool_output.truncate !== false && source.tool_output.truncate !== false) return merged
-
-  // Disabled truncation and custom limits are separate config modes; the later layer selects the mode.
-  merged.tool_output = source.tool_output
-  return merged
+  return mergeDeep(target, source) as Info
 }
 
 function mergeConfigConcatArrays(target: Info, source: Info): Info {
@@ -260,13 +254,8 @@ export const Info = Schema.Struct({
   ),
   tool_output: Schema.optional(
     Schema.Union([
+      Schema.Literal(false).annotate({ description: "Disable tool output truncation" }),
       Schema.Struct({
-        truncate: Schema.Literal(false).annotate({ description: "Disable tool output truncation" }),
-      }).annotate({ parseOptions: { onExcessProperty: "error" } }),
-      Schema.Struct({
-        truncate: Schema.optional(Schema.Literal(true)).annotate({
-          description: "Enable truncating tool output that exceeds the configured limits (default: true)",
-        }),
         max_lines: Schema.optional(PositiveInt).annotate({
           description: "Maximum lines of tool output before it is truncated and saved to disk (default: 2000)",
         }),

packages/opencode/src/tool/truncate.ts

@@ -42,7 +42,7 @@ export interface Interface {
   readonly output: (text: string, options?: Options, agent?: Agent.Info) => Effect.Effect<Result>
   /**
    * Resolved truncation limits from `tool_output` in opencode config.
-   * Returns `None` when the user has disabled truncation (`tool_output.truncate: false`),
+   * Returns `None` when the user has disabled truncation (`tool_output: false`),
    * in which case callers should pass output through without enforcing thresholds.
    */
   readonly limits: () => Effect.Effect<Option.Option<Limits>>
@@ -81,7 +81,7 @@ export const layer = Layer.effect(
       if (Option.isNone(configSvc)) return Option.some({ maxLines: MAX_LINES, maxBytes: MAX_BYTES })
       const cfg = yield* configSvc.value.get().pipe(Effect.catch(() => Effect.succeed(undefined)))
       const tool_output = cfg?.tool_output
-      if (tool_output?.truncate === false) return Option.none<Limits>()
+      if (tool_output === false) return Option.none<Limits>()
       return Option.some({
         maxLines: tool_output?.max_lines ?? MAX_LINES,
         maxBytes: tool_output?.max_bytes ?? MAX_BYTES,

packages/opencode/test/config/config.test.ts

@@ -1292,25 +1292,20 @@ test("config parser preserves permission order while rejecting unknown top-level
   }
 })
 
-test("tool_output only accepts thresholds when truncation is enabled", () => {
-  expect(ConfigParse.schema(Config.Info, { tool_output: { truncate: false } }, "test").tool_output).toEqual({
-    truncate: false,
-  })
+test("tool_output accepts thresholds or disables truncation", () => {
+  expect(ConfigParse.schema(Config.Info, { tool_output: false }, "test").tool_output).toBe(false)
   expect(
     ConfigParse.schema(Config.Info, { tool_output: { max_lines: 200, max_bytes: 8192 } }, "test").tool_output,
   ).toEqual({
     max_lines: 200,
     max_bytes: 8192,
   })
-  expect(() =>
-    ConfigParse.schema(Config.Info, { tool_output: { truncate: false, max_lines: 200, max_bytes: 8192 } }, "test"),
-  ).toThrow()
 })
 
 it.effect("project tool_output limits replace disabled global truncation", () =>
   withConfigTree(
     {
-      global: { tool_output: { truncate: false } },
+      global: { tool_output: false },
       project: { tool_output: { max_lines: 200 } },
     },
     Effect.gen(function* () {
@@ -1323,10 +1318,10 @@ it.effect("project disabled tool_output replaces global limits", () =>
   withConfigTree(
     {
       global: { tool_output: { max_lines: 200, max_bytes: 8192 } },
-      project: { tool_output: { truncate: false } },
+      project: { tool_output: false },
     },
     Effect.gen(function* () {
-      expect((yield* Config.use.get()).tool_output).toEqual({ truncate: false })
+      expect((yield* Config.use.get()).tool_output).toBe(false)
     }),
   ),
 )

packages/opencode/test/tool/shell.test.ts

@@ -1207,7 +1207,7 @@ describe("tool.shell truncation", () => {
 
   it.live("does not truncate output when tool_output is disabled", () =>
     Effect.gen(function* () {
-      const tmp = yield* tmpdirScoped({ config: { tool_output: { truncate: false } } })
+      const tmp = yield* tmpdirScoped({ config: { tool_output: false } })
       yield* runIn(
         tmp,
         Effect.gen(function* () {

packages/opencode/test/tool/truncation.test.ts

@@ -166,7 +166,7 @@ describe("Truncate", () => {
         }),
       )
 
-      const disabledIt = configuredIt({ tool_output: { truncate: false } })
+      const disabledIt = configuredIt({ tool_output: false })
       disabledIt.live("does not truncate output when disabled", () =>
         Effect.gen(function* () {
           const content = "a".repeat(Truncate.MAX_BYTES + 1)

packages/sdk/js/src/v2/gen/types.gen.ts

@@ -1298,14 +1298,8 @@ export type Config = {
    * Configure tool output truncation. When output exceeds either limit, the full text is written to the truncation directory and a preview is returned.
    */
   tool_output?:
+    | false
     | {
-        /**
-         * Disable tool output truncation
-         */
-        truncate: false
-      }
-    | {
-        truncate?: true
         max_lines?: number
         max_bytes?: number
       }

packages/web/src/content/docs/config.mdx

@@ -361,32 +361,26 @@ You can control when tool output is truncated using the `tool_output` option. Wh
 {
   "$schema": "https://opencode.ai/config.json",
   "tool_output": {
-    "truncate": true,
     "max_lines": 2000,
     "max_bytes": 51200
   }
 }
 ```
 
-- `truncate` - Truncate tool output when it exceeds a configured threshold (default: `true`).
 - `max_lines` - Maximum number of lines before output is truncated (default: `2000`).
 - `max_bytes` - Maximum size in bytes before output is truncated (default: `51200`).
 
 These thresholds apply to output handled by OpenCode's shared truncation layer, including MCP and plugin tool output. Individual tools that page or cap their own results can have separate limits.
 
-To disable shared tool output truncation, set `truncate` to `false`:
+To disable shared tool output truncation, set `tool_output` to `false`:
 
 ```json title="opencode.json"
 {
   "$schema": "https://opencode.ai/config.json",
-  "tool_output": {
-    "truncate": false
-  }
+  "tool_output": false
 }
 ```
 
-`truncate: false` cannot be combined with `max_lines` or `max_bytes`; thresholds only apply when truncation is enabled.
-
 ---
 
 ### Models