fix(agents): surface disk full session write errors (#61264)

CHANGELOG.md

@@ -134,6 +134,7 @@ Docs: https://docs.openclaw.ai
 - Exec/heartbeat: use the canonical `exec-event` wake reason for `notifyOnExit` so background exec completions still trigger follow-up turns when `HEARTBEAT.md` is empty or comments-only. (#41479) Thanks @rstar327.
 - Heartbeat: skip wake delivery when the target session lane is already busy so the pending event is retried instead of getting drained too early. (#40526) Thanks @lucky7323.
 - Plugin SDK/context engines: export the missing context-engine result and subagent lifecycle types from `openclaw/plugin-sdk` so context engine plugins can type `ContextEngine` implementations without local workarounds. (#61251) Thanks @DaevMithran.
+- Agents/errors: surface an explicit disk-full message when local session or transcript writes fail with `ENOSPC`/`disk full`, so those runs stop degrading into opaque `NO_REPLY`-style failures. Thanks @vincentkoc.
 
 ## 2026.4.2
 

src/agents/pi-embedded-helpers.formatassistanterrortext.test.ts

@@ -191,6 +191,16 @@ describe("formatAssistantErrorText", () => {
     );
   });
 
+  it.each(["disk full", "ENOSPC: no space left on device, write"])(
+    "returns a friendly disk-space message for %s",
+    (errorMessage) => {
+      const msg = makeAssistantError(errorMessage);
+      expect(formatAssistantErrorText(msg)).toBe(
+        "OpenClaw could not write local session data because the disk is full. Free some disk space and try again.",
+      );
+    },
+  );
+
   it("returns a DNS-specific message for provider lookup failures", () => {
     const msg = makeAssistantError("dial tcp: lookup api.example.com: no such host (ENOTFOUND)");
     expect(formatAssistantErrorText(msg)).toBe(

src/agents/pi-embedded-helpers.sanitizeuserfacingtext.test.ts

@@ -149,6 +149,15 @@ describe("sanitizeUserFacingText", () => {
     ).toBe("LLM request failed: connection refused by the provider endpoint.");
   });
 
+  it.each(["disk full", "ENOSPC: no space left on device"])(
+    "rewrites disk-space failures with errorContext: %s",
+    (input) => {
+      expect(sanitizeUserFacingText(input, { errorContext: true })).toBe(
+        "OpenClaw could not write local session data because the disk is full. Free some disk space and try again.",
+      );
+    },
+  );
+
   it("sanitizes invalid streaming event order errors", () => {
     expect(
       sanitizeUserFacingText(

src/agents/pi-embedded-helpers/errors.ts

@@ -167,6 +167,24 @@ function formatTransportErrorCopy(raw: string): string | undefined {
   return undefined;
 }
 
+function formatDiskSpaceErrorCopy(raw: string): string | undefined {
+  if (!raw) {
+    return undefined;
+  }
+  const lower = raw.toLowerCase();
+  if (
+    /\benospc\b/i.test(raw) ||
+    lower.includes("no space left on device") ||
+    lower.includes("disk full")
+  ) {
+    return (
+      "OpenClaw could not write local session data because the disk is full. " +
+      "Free some disk space and try again."
+    );
+  }
+  return undefined;
+}
+
 function isReasoningConstraintErrorMessage(raw: string): boolean {
   if (!raw) {
     return false;
@@ -925,6 +943,11 @@ export function formatAssistantErrorText(
     }
   }
 
+  const diskSpaceCopy = formatDiskSpaceErrorCopy(raw);
+  if (diskSpaceCopy) {
+    return diskSpaceCopy;
+  }
+
   if (isContextOverflowError(raw)) {
     return (
       "Context overflow: prompt too large for the model. " +
@@ -1023,6 +1046,11 @@ export function sanitizeUserFacingText(text: unknown, opts?: { errorContext?: bo
       return execDeniedMessage;
     }
 
+    const diskSpaceCopy = formatDiskSpaceErrorCopy(trimmed);
+    if (diskSpaceCopy) {
+      return diskSpaceCopy;
+    }
+
     if (/incorrect role information|roles must alternate/i.test(trimmed)) {
       return (
         "Message ordering conflict - please try again. " +