diff --git a/packages/coding-agent/src/prompts/tools/task.md b/packages/coding-agent/src/prompts/tools/task.md
index 4b192a888..72fe69ac5 100644
--- a/packages/coding-agent/src/prompts/tools/task.md
+++ b/packages/coding-agent/src/prompts/tools/task.md
@@ -7,11 +7,10 @@ Execution blocks your turn: the call only returns once the work is completely fi
 - **Sequence only when necessary:** The only reason to run A before B is if B strictly requires A's output to function (e.g., a core API contract or schema migration). {{#if ircEnabled}}If the missing piece is small, run them in parallel and have B ask A via `irc`!{{/if}}
 - **Role matching:** Assign each subagent a specific `role` (e.g. "Security Reviewer", "DB Migrator"). Do not spawn generic workers.
 - **No overhead:** Each assignment MUST instruct its agent to skip formatters, linters, and project-wide test suites. You will run those once at the end.
-- **Do your own thinking:** NEVER assign reasoning, architecture, or design to `quick_task` or `explore`. They are for mechanical lookups only. Keep hard decisions in your own context or use `task`, `plan`, or `oracle`.
 - **One-pass agents:** Prefer agents that investigate **and** edit in a single pass; only spin a read-only discovery step (e.g. `explore`) when the affected files are genuinely unknown.
 
 # Inputs
-- `agent`: The base agent type to use (e.g., `task`, `explore`).
+- `agent` (optional): The base agent type to use (e.g., `explore`, `reviewer`). Defaults to `task` (the general-purpose worker) — omit it for the default worker instead of passing `agent: "task"`.
 {{#if batchEnabled}}
 - `context`: Shared project state, constraints, and contracts. Applies to the entire batch; do not duplicate this background into individual tasks.
 - `tasks[]`: Array of subagents to spawn.
@@ -37,13 +36,7 @@ Subagents start blank. They have no access to your conversation history.
 {{#if batchEnabled}}
 - Pass large payloads using `local://<path>` URIs, never inline text.
 {{else}}
-- *Note: The single-spawn shape has no `context` field.* Write shared project state ONCE to a `local://` file (e.g., `local://ctx.md`) and reference that URL in your assignments. Pass large payloads using `local://<path>` URIs, never inline text.
-{{/if}}
-{{#if ircEnabled}}
-- Once spawned, coordinate with live agents via `irc` using their IDs. If task B depends on task A, B SHOULD message A directly.
-{{/if}}
-{{#if asyncEnabled}}
-- If you run out of things to do and are genuinely blocked waiting for a subagent, use `job poll`. Use `job cancel` only for stalled work.
+- Write shared project state ONCE to a `local://` file (e.g., `local://ctx.md`) and reference that URL in your assignments.
 {{/if}}
 
 # Format Contracts
diff --git a/packages/coding-agent/src/task/executor.ts b/packages/coding-agent/src/task/executor.ts
index 76bf4e034..d0f718f00 100644
--- a/packages/coding-agent/src/task/executor.ts
+++ b/packages/coding-agent/src/task/executor.ts
@@ -87,7 +87,7 @@ const MCP_CALL_TIMEOUT_MS = 60_000;
  */
 export const SOFT_REQUEST_BUDGET: Record<string, number> = {
 	explore: 40,
-	quick_task: 40,
+	sonic: 40,
 	default: 90,
 };
 
diff --git a/packages/coding-agent/src/task/index.ts b/packages/coding-agent/src/task/index.ts
index d61208f65..c48c7e876 100644
--- a/packages/coding-agent/src/task/index.ts
+++ b/packages/coding-agent/src/task/index.ts
@@ -243,8 +243,11 @@ function validateShapeParams(batchEnabled: boolean, params: TaskParams): string
 }
 
 /**
- * Validate the spawn parameter contract against the wire shapes. `agent` is
- * always required. With `task.batch` the model-facing shape is
+ * Validate the spawn parameter contract against the wire shapes. `agent`
+ * defaults to `task` (the schema default; `execute` normalizes the same way for
+ * direct callers), so the missing-`agent` guard only fires for callers that
+ * invoke this validator with an unnormalized blank agent. With `task.batch` the
+ * model-facing shape is
  * `{ agent, context, tasks[] }` — `tasks` non-empty with per-item assignments
  * and unique ids, `context` non-empty, no top-level `assignment` alongside.
  * The flat `{ agent, ...item }` form stays accepted at runtime under either
@@ -328,14 +331,17 @@ function spawnParamsFor(params: TaskParams, item: TaskItem): TaskParams {
 	return spawn;
 }
 
+/** Agent type spawned when a `task` call omits `agent`; mirrors the schema default in `getTaskSchema`. */
+const DEFAULT_TASK_AGENT = "task";
+
 /** Generic worker agents whose output sharpens with a tailored `role` rather than the bare type. */
-const GENERIC_SPAWN_AGENTS: ReadonlySet<string> = new Set(["task", "quick_task"]);
+const GENERIC_SPAWN_AGENTS: ReadonlySet<string> = new Set(["task", "sonic"]);
 
 /**
  * Advisory — never a rejection — nudging the spawner toward tailored
  * specialists when it spawns generic role-less workers and still holds spawn
  * capacity (DepthCapacity: it currently has the `task` tool). Fires when a
- * generic `task`/`quick_task` spawn carries no `role`, or when one call clones
+ * generic `task`/`sonic` spawn carries no `role`, or when one call clones
  * the same agent ≥2× all without roles. Returns undefined when no nudge applies.
  */
 export function buildSpecializationAdvisory(
@@ -559,7 +565,14 @@ export class TaskTool implements AgentTool<TaskToolSchemaInstance, TaskToolDetai
 		signal?: AbortSignal,
 		onUpdate?: AgentToolUpdateCallback<TaskToolDetails>,
 	): Promise<AgentToolResult<TaskToolDetails>> {
-		const params = repairTaskParams(rawParams as TaskParams);
+		const repaired = repairTaskParams(rawParams as TaskParams);
+		// The schema defaults `agent` to `task` for model calls, but internal
+		// callers and stale transcripts build params directly and bypass arktype.
+		// Normalize once here so every downstream path sees the resolved agent.
+		const params =
+			typeof repaired.agent === "string" && repaired.agent.trim() !== ""
+				? repaired
+				: { ...repaired, agent: DEFAULT_TASK_AGENT };
 		const batchEnabled = this.#isBatchEnabled();
 		const validationError = validateShapeParams(batchEnabled, params) ?? validateSpawnParams(params, batchEnabled);
 		if (validationError) {
diff --git a/packages/coding-agent/src/task/types.ts b/packages/coding-agent/src/task/types.ts
index adb3b4647..40faf390c 100644
--- a/packages/coding-agent/src/task/types.ts
+++ b/packages/coding-agent/src/task/types.ts
@@ -111,7 +111,7 @@ export interface TaskItem {
 }
 
 export const taskSchema = type({
-	agent: "string",
+	agent: "string = 'task'",
 	"id?": "string",
 	"description?": "string",
 	"role?": ROLE_INPUT_SCHEMA,
@@ -120,7 +120,7 @@ export const taskSchema = type({
 	"+": "delete",
 });
 const taskSchemaNoIsolation = type({
-	agent: "string",
+	agent: "string = 'task'",
 	"id?": "string",
 	"description?": "string",
 	"role?": ROLE_INPUT_SCHEMA,
@@ -128,13 +128,13 @@ const taskSchemaNoIsolation = type({
 	"+": "delete",
 });
 const taskSchemaBatch = type({
-	agent: "string",
+	agent: "string = 'task'",
 	context: "string",
 	tasks: taskItemSchemaIsolated.array(),
 	"+": "delete",
 });
 const taskSchemaBatchNoIsolation = type({
-	agent: "string",
+	agent: "string = 'task'",
 	context: "string",
 	tasks: taskItemSchema.array(),
 	"+": "delete",
@@ -160,7 +160,7 @@ export function getTaskSchema(options: { isolationEnabled: boolean; batchEnabled
  * transcripts using the flat form keep working under either setting.
  */
 export interface TaskParams {
-	/** Agent type; required. */
+	/** Agent type to spawn; defaults to `"task"` (the general-purpose worker) when omitted. */
 	agent?: string;
 	/** Stable agent id (flat form); default = generated AdjectiveNoun. */
 	id?: string;