diff --git a/src/responses/function-call-compat.ts b/src/responses/function-call-compat.ts
index c4888cf1f7..fc26675dc1 100644
--- a/src/responses/function-call-compat.ts
+++ b/src/responses/function-call-compat.ts
@@ -33,6 +33,38 @@ function namespaceOf(value: unknown): string | undefined {
   return typeof value === "string" && value !== "functions" ? value : undefined;
 }
 
+/**
+ * Repair one provider spelling drift for Codex's flat shell bridge.
+ *
+ * This is schema-bound rather than a general alias: `input` is also a legitimate
+ * argument name for arbitrary caller and MCP tools. Only the exact bare
+ * `exec_command` declaration can establish that its sole string input has one faithful
+ * reading as the required string `cmd` member.
+ */
+function repairExecCommandInput(
+  argumentsText: string,
+  schema: FunctionCallRepairSchema,
+): string {
+  if (schema.namespace !== undefined || schema.name !== "exec_command") return argumentsText;
+  const parameters = schema.parameters;
+  if (!isObject(parameters) || parameters.type !== "object"
+    || !Array.isArray(parameters.required) || !parameters.required.includes("cmd")
+    || !isObject(parameters.properties) || !isObject(parameters.properties.cmd)
+    || parameters.properties.cmd.type !== "string") return argumentsText;
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(argumentsText);
+  } catch {
+    return argumentsText;
+  }
+  if (!isObject(parsed)) return argumentsText;
+  const keys = Object.keys(parsed);
+  if (keys.length !== 1 || keys[0] !== "input" || typeof parsed.input !== "string") {
+    return argumentsText;
+  }
+  return JSON.stringify({ cmd: parsed.input });
+}
+
 function selectorAllows(
   selector: unknown,
   lowered: unknown,
@@ -131,7 +163,12 @@ function repairItem(item: unknown, schemas: FunctionCallRepairSchemas, completed
       if (unsafe) return item;
     } catch { return item; }
   }
-  const argumentsText = coerceIntegerToolArguments(raw || "{}", schema.parameters, schema.namespace ? undefined : schema.name);
+  const integerRepaired = coerceIntegerToolArguments(
+    raw || "{}",
+    schema.parameters,
+    schema.namespace ? undefined : schema.name,
+  );
+  const argumentsText = repairExecCommandInput(integerRepaired, schema);
   return argumentsText === raw ? item : { ...item, arguments: argumentsText };
 }
 
diff --git a/structure/decisions/ADR-0098-schema-bound-exec-command-input-repair.md b/structure/decisions/ADR-0098-schema-bound-exec-command-input-repair.md
new file mode 100644
index 0000000000..8640b675e4
--- /dev/null
+++ b/structure/decisions/ADR-0098-schema-bound-exec-command-input-repair.md
@@ -0,0 +1,12 @@
+# ADR-0098 — decision recorded under "Schema-bound flat shell repair"
+
+- Contract owner: [transports/responses.md](../transports/responses.md#schema-bound-flat-shell-repair)
+
+## Decision record
+
+- 목적과 의도: Let an unambiguous routed `exec_command` wrapper reach the Codex shell bridge without weakening tool identity or argument validation.
+- 기존 구현 및 제약 조건: Freeform code-mode tools already unwrap `input`, but a genuinely declared flat function must keep its name and Codex validates it against required `cmd`.
+- 검토한 주요 대안: Rename the call to code-mode `exec`; rewrite every function's `input`; add a schema-bound repair at authoritative function-call completion.
+- 선택한 방식: Repair only the exact bare declaration and exact one-member string payload when the current-turn schema requires string `cmd`.
+- 다른 대안 대신 이 방식을 선택한 이유: Tool names and arbitrary `input` fields are caller-owned; the original schema is the only authority that makes the representation change deterministic.
+- 장점, 단점 및 영향: Buffered, streamed-completion, and replay paths converge on valid `cmd` arguments; previews and ambiguous or namespaced shapes stay untouched.
diff --git a/structure/transports/responses.md b/structure/transports/responses.md
index b4399c97ba..f1fd790353 100644
--- a/structure/transports/responses.md
+++ b/structure/transports/responses.md
@@ -125,6 +125,16 @@ Function-call wrappers around freeform bodies are restored by
 is recoverable because the wrapper is otherwise unusable; two alternate fields are ambiguous and
 therefore remain untouched. Foreign freeform grammars never receive that compatibility rewrite.
 
+#### Schema-bound flat shell repair
+
+Completed Responses function calls have one separate schema-bound flat-shell repair. When the
+exact bare `exec_command` declaration requires a string `cmd`, a provider result containing only
+the string member `{ "input": "..." }` is rewritten to `{ "cmd": "..." }`; the call name is not
+changed. Namespaced tools, additional or conflicting members, non-string values, malformed JSON,
+partial streaming previews, and schemas that do not prove this exact contract remain byte-exact.
+
+> Decision record: [ADR-0098](../decisions/ADR-0098-schema-bound-exec-command-input-repair.md)
+
 Progressive preview for those wrappers is decoded by
 `src/responses/progressive-freeform-input.ts` in both the adapter-event bridge and routed
 function-call restoration, over the classification in `src/responses/freeform-wrapper-scan.ts`.
diff --git a/tests/responses/responses-function-tool-repair.test.ts b/tests/responses/responses-function-tool-repair.test.ts
index 599e9cd9fa..7577ac1559 100644
--- a/tests/responses/responses-function-tool-repair.test.ts
+++ b/tests/responses/responses-function-tool-repair.test.ts
@@ -211,6 +211,77 @@ describe("pure function completion repair", () => {
     expect(repairFunctionCalls(missing, schemas).value).toBe(missing);
   });
 
+  test("repairs the exact flat exec_command input wrapper into its required cmd", () => {
+    const shell = {
+      type: "function",
+      name: "exec_command",
+      parameters: {
+        type: "object",
+        properties: { cmd: { type: "string" } },
+        required: ["cmd"],
+        additionalProperties: false,
+      },
+    };
+    const map = collectFunctionCallRepairSchemas({ tools: [shell] });
+    const call = item('{"input":"printf hello"}', { name: "exec_command" });
+    expect(repairFunctionCalls(call, map).value)
+      .toEqual({ ...call, arguments: '{"cmd":"printf hello"}' });
+
+    const reserved = item('{"input":"printf hello"}', {
+      name: "exec_command",
+      namespace: "functions",
+    });
+    expect(repairFunctionCalls(reserved, map).value)
+      .toEqual({ ...reserved, arguments: '{"cmd":"printf hello"}' });
+  });
+
+  test("exec_command input repair stays fail-closed outside the exact schema and payload", () => {
+    const declaration = (parameters: Record<string, unknown>, namespace?: string) => ({
+      type: "function",
+      name: "exec_command",
+      ...(namespace ? { namespace } : {}),
+      parameters,
+    });
+    const canonical = {
+      type: "object",
+      properties: { cmd: { type: "string" } },
+      required: ["cmd"],
+    };
+    const cases: Array<{ payload: string; tool?: ReturnType<typeof declaration> }> = [
+      { payload: '{"cmd":"already canonical"}' },
+      { payload: '{"input":"one","cwd":"/tmp"}' },
+      { payload: '{"input":7}' },
+      { payload: '{"input":"one","cmd":"two"}' },
+      { payload: '{"input":"one"', },
+      { payload: '{"input":"one"}', tool: declaration({ ...canonical, required: [] }) },
+      { payload: '{"input":"one"}', tool: declaration({ ...canonical, properties: { cmd: { type: "number" } } }) },
+    ];
+    for (const entry of cases) {
+      const tool = entry.tool ?? declaration(canonical);
+      const map = collectFunctionCallRepairSchemas({ tools: [tool] });
+      const namespace = tool.namespace;
+      const call = item(entry.payload, {
+        name: namespace ? `${namespace}__exec_command` : "exec_command",
+        ...(namespace ? { namespace } : {}),
+      });
+      expect(repairFunctionCalls(call, map).value).toBe(call);
+    }
+
+    // A namespace is declared by its group, not by a `namespace` property on a
+    // top-level function. Exercise the actual remote identity so this proves the
+    // bare-only repair guard rather than passing because schema lookup missed.
+    const remoteMap = collectFunctionCallRepairSchemas({ tools: [{
+      type: "namespace",
+      name: "remote",
+      tools: [declaration(canonical)],
+    }] });
+    const remoteCall = item('{"input":"one"}', {
+      name: "exec_command",
+      namespace: "remote",
+    });
+    expect(repairFunctionCalls(remoteCall, remoteMap).value).toBe(remoteCall);
+  });
+
   test.each([" ", "{", '{"cell_id":4.5}', '{"yield_time_ms":1.5}', '{"union":4.0}',
     '{"cell_id":9007199254740993}', '{"cell_id":4,"unknown":9007199254740993}', '{"cell_id":4,"unknown":1e400}'])
   ("preserves invalid/disagreeing/unsafe payload %s", argumentsText => {
@@ -269,6 +340,36 @@ describe("native function completion SSE", () => {
     } finally { rewrite.dispose?.(); budget.dispose(); }
   });
 
+  test("repairs exec_command input only at authoritative SSE completion boundaries", () => {
+    const map = collectFunctionCallRepairSchemas({ tools: [{
+      type: "function",
+      name: "exec_command",
+      parameters: {
+        type: "object",
+        properties: { cmd: { type: "string" } },
+        required: ["cmd"],
+      },
+    }] });
+    const rewrite = createResponsesFunctionToolRepairBlockRewrite(map);
+    const shellItem = item("", { name: "exec_command", status: "in_progress" });
+    try {
+      const added = frame("response.output_item.added", { output_index: 0, item: shellItem });
+      const delta = frame("response.function_call_arguments.delta", {
+        item_id: "fc_one",
+        delta: '{"input":"printf hello"}',
+      });
+      expect(rewrite(added)).toEqual([added]);
+      expect(rewrite(delta)).toEqual([delta]);
+      const done = rewrite(frame("response.function_call_arguments.done", {
+        item_id: "fc_one",
+        arguments: '{"input":"printf hello"}',
+      }));
+      expect(payload(done[0]!)).toMatchObject({ arguments: '{"cmd":"printf hello"}' });
+    } finally {
+      rewrite.dispose?.();
+    }
+  });
+
   test.each(["response.output_item.done", "response.completed"])("no-arg %s works without arguments.done", type => {
     const rewrite = createResponsesFunctionToolRepairBlockRewrite(schemas);
     try {