diff --git a/packages/cli/script/generate-sdk.ts b/packages/cli/script/generate-sdk.ts
index 19f953cc6..743ec6f3f 100644
--- a/packages/cli/script/generate-sdk.ts
+++ b/packages/cli/script/generate-sdk.ts
@@ -633,11 +633,14 @@ for (const { path, command } of allCommands) {
       return `${camelCase(name)}: ${flag?.tsType ?? "string"}`;
     });
     const streamingConstraint = streamingFlagTypes.join("; ");
+    const streamingRest = hasVariadicPositional
+      ? ", ...positional: string[]"
+      : "";
 
     typeDecl = [
       `${indent}    /** ${brief} */`,
       `${indent}    ${methodName}: {`,
-      `${indent}      (params: ${params?.name ?? "Record<string, never>"} & { ${streamingConstraint} }): AsyncIterable<unknown>;`,
+      `${indent}      (params: ${params?.name ?? "Record<string, never>"} & { ${streamingConstraint} }${streamingRest}): AsyncIterable<unknown>;`,
       `${indent}      ${sig}: Promise<${returnType}>;`,
       `${indent}    };`,
     ].join("\n");
diff --git a/packages/cli/src/lib/sdk-invoke.ts b/packages/cli/src/lib/sdk-invoke.ts
index 1cb859571..bd44c4356 100644
--- a/packages/cli/src/lib/sdk-invoke.ts
+++ b/packages/cli/src/lib/sdk-invoke.ts
@@ -74,7 +74,8 @@ export type FlagDef = {
   default?: unknown;
   optional?: boolean;
   parse?: (value: string) => unknown;
-  variadic?: boolean;
+  /** `true` or a separator string — Stricli collects either form into an array. */
+  variadic?: boolean | string;
 };
 
 /** Resolved command: handler function + flag definitions for default application. */
@@ -161,6 +162,9 @@ function resolveFlagDefault(def: FlagDef): unknown {
  *   (same as Stricli's `parseInput` path in `parseInputsForFlag`).
  * - For `kind: "boolean"` / `kind: "enum"` flags with a `default`, uses the raw value.
  * - Skips flags already set (non-`undefined`) by the caller.
+ * - Wraps a scalar caller value for a variadic flag in an array. Stricli always
+ *   hands variadic flags to the handler as arrays, so an untyped caller passing
+ *   `{ field: "title" }` would otherwise crash on array methods (CLI-28C).
  *
  * @param flags - The flags object from the SDK caller (may have `undefined` values).
  * @param flagDefs - The command's Stricli flag definitions.
@@ -174,9 +178,11 @@ export function applyFlagDefaults(
   // Copy caller-provided flags, skipping undefined values so they
   // don't shadow the defaults we're about to apply.
   for (const [key, value] of Object.entries(flags)) {
-    if (value !== undefined) {
-      result[key] = value;
+    if (value === undefined) {
+      continue;
     }
+    result[key] =
+      flagDefs[key]?.variadic && !Array.isArray(value) ? [value] : value;
   }
   // Apply defaults for any flag not already set by the caller
   for (const [name, def] of Object.entries(flagDefs)) {
diff --git a/packages/cli/test/lib/sdk-flag-types.test.ts b/packages/cli/test/lib/sdk-flag-types.test.ts
index 279618931..abbd65d2d 100644
--- a/packages/cli/test/lib/sdk-flag-types.test.ts
+++ b/packages/cli/test/lib/sdk-flag-types.test.ts
@@ -30,4 +30,15 @@ describe("generated SDK flag types", () => {
     expect(login).toContain("scope?: Array<string>;");
     expect(login).toContain("token?: string;");
   });
+
+  test("streaming overloads accept the target positional", () => {
+    // Streaming calls still take their target as trailing positionals, e.g.
+    // `sdk.log.list({ follow: "5" }, "org/project")` must type as an AsyncIterable.
+    expect(declarations).toContain(
+      "(params: LogListParams & { follow: string }, ...positional: string[]): AsyncIterable<unknown>;",
+    );
+    expect(declarations).toContain(
+      "(params: DashboardViewParams & { refresh: string }, ...positional: string[]): AsyncIterable<unknown>;",
+    );
+  });
 });
diff --git a/packages/cli/test/lib/sdk-invoke.test.ts b/packages/cli/test/lib/sdk-invoke.test.ts
index 7d2c8b764..c477d6230 100644
--- a/packages/cli/test/lib/sdk-invoke.test.ts
+++ b/packages/cli/test/lib/sdk-invoke.test.ts
@@ -104,6 +104,40 @@ describe("applyFlagDefaults: boolean flags", () => {
   });
 });
 
+// ---------------------------------------------------------------------------
+// applyFlagDefaults — variadic flags
+// ---------------------------------------------------------------------------
+
+describe("applyFlagDefaults: variadic flags", () => {
+  const flagDefs: Record<string, FlagDef> = {
+    field: { kind: "parsed", parse: String, variadic: true, optional: true },
+    environment: {
+      kind: "parsed",
+      parse: String,
+      variadic: ",",
+      optional: true,
+    },
+    dataset: { kind: "parsed", parse: String, optional: true },
+  };
+
+  test("wraps a scalar caller value in an array", () => {
+    // Stricli always hands variadic flags to the handler as arrays (CLI-28C).
+    const result = applyFlagDefaults(
+      { field: "title", environment: "prod", dataset: "spans" },
+      flagDefs,
+    );
+    expect(result.field).toEqual(["title"]);
+    expect(result.environment).toEqual(["prod"]);
+    expect(result.dataset).toBe("spans");
+  });
+
+  test("keeps caller arrays unchanged", () => {
+    const fields = ["title", "count()"];
+    const result = applyFlagDefaults({ field: fields }, flagDefs);
+    expect(result.field).toBe(fields);
+  });
+});
+
 // ---------------------------------------------------------------------------
 // applyFlagDefaults — enum flags
 // ---------------------------------------------------------------------------