diff --git a/apps/mobile/src/features/cloud/cloudDebugLog.ts b/apps/mobile/src/features/cloud/cloudDebugLog.ts
index 840a3db55680f3c874f2010f940497ec85c7f53b..7e57b39b7bb88c848ff0ca7eec2df55270f5cb53 100644
--- a/apps/mobile/src/features/cloud/cloudDebugLog.ts
+++ b/apps/mobile/src/features/cloud/cloudDebugLog.ts
@@ -1,18 +1,14 @@
+import { createDebugLogger } from "../../lib/debugLog";
+
+const logger = createDebugLogger("cloud", {
+  enabledInDev: true,
+  legacyGlobalFlag: "__T3_CLOUD_DEBUG__",
+});
+
 export function isCloudDebugEnabled(): boolean {
-  return (
-    (typeof __DEV__ !== "undefined" && __DEV__) ||
-    (typeof globalThis !== "undefined" &&
-      (globalThis as { __T3_CLOUD_DEBUG__?: boolean }).__T3_CLOUD_DEBUG__ === true)
-  );
+  return logger.isEnabled();
 }
 
 export function cloudDebugLog(event: string, data?: Record<string, unknown>): void {
-  if (!isCloudDebugEnabled()) {
-    return;
-  }
-  if (data) {
-    console.log(`[t3-cloud] ${event}`, data);
-  } else {
-    console.log(`[t3-cloud] ${event}`);
-  }
+  logger.log(event, data);
 }
diff --git a/apps/mobile/src/features/terminal/terminalDebugLog.ts b/apps/mobile/src/features/terminal/terminalDebugLog.ts
index eb11419b330cc17f82d0442acef146f76cd5e1af..31c8497915c39d0127e0ae3aa649e8ade486dc24 100644
--- a/apps/mobile/src/features/terminal/terminalDebugLog.ts
+++ b/apps/mobile/src/features/terminal/terminalDebugLog.ts
@@ -1,24 +1,21 @@
+import { createDebugLogger } from "../../lib/debugLog";
+
 /**
  * Debug logging for the mobile terminal pipeline. Prefix: `[t3-terminal]`.
  *
- * Enabled when `__DEV__` is true, or set `globalThis.__T3_TERMINAL_DEBUG__ = true` in a JS
- * debugger / Metro console to trace release/TestFlight builds.
+ * Enabled when `__DEV__` is true, or set `globalThis.__T3_TERMINAL_DEBUG__`
+ * (or the shared `globalThis.__T3_DEBUG__` filter) in a JS debugger / Metro
+ * console to trace release/TestFlight builds.
  */
+const logger = createDebugLogger("terminal", {
+  enabledInDev: true,
+  legacyGlobalFlag: "__T3_TERMINAL_DEBUG__",
+});
+
 export function isTerminalDebugEnabled(): boolean {
-  return (
-    (typeof __DEV__ !== "undefined" && __DEV__) ||
-    (typeof globalThis !== "undefined" &&
-      (globalThis as { __T3_TERMINAL_DEBUG__?: boolean }).__T3_TERMINAL_DEBUG__ === true)
-  );
+  return logger.isEnabled();
 }
 
 export function terminalDebugLog(message: string, data?: Record<string, unknown>): void {
-  if (!isTerminalDebugEnabled()) {
-    return;
-  }
-  if (data !== undefined) {
-    console.log(`[t3-terminal] ${message}`, data);
-  } else {
-    console.log(`[t3-terminal] ${message}`);
-  }
+  logger.log(message, data);
 }
diff --git a/apps/mobile/src/lib/debugLog.ts b/apps/mobile/src/lib/debugLog.ts
new file mode 100644
index 0000000000000000000000000000000000000000..447973503333bbcf00aa5e7a8078bf41389151a9
--- /dev/null
+++ b/apps/mobile/src/lib/debugLog.ts
@@ -0,0 +1,64 @@
+/**
+ * Namespaced, filterable debug logging shared by mobile subsystems.
+ *
+ * Ordinary, expected conditions — a queued send failing while the device is
+ * offline, for example — go through a debug logger instead of `console.warn`
+ * so warning output stays reserved for failures someone can act on. Output
+ * uses `console.log` with a `[t3-<namespace>]` prefix, matching the existing
+ * cloud and terminal debug logs. (client-runtime cannot host this: its
+ * tooling bans `console.*` in favor of Effect logging.)
+ *
+ * A logger is silent in every build, including development, unless enabled.
+ * Toggle it from a JS debugger or the Metro console, including on release/TestFlight builds:
+ * - `globalThis.__T3_DEBUG__ = true` enables every namespace;
+ * - `globalThis.__T3_DEBUG__ = ["thread-outbox"]` enables only listed ones.
+ *
+ * Subsystems whose traces are useful by default in development (`__DEV__`)
+ * opt in with `enabledInDev`; `legacyGlobalFlag` keeps an older
+ * subsystem-specific global (e.g. `__T3_CLOUD_DEBUG__`) working.
+ */
+
+export interface DebugLogger {
+  readonly isEnabled: () => boolean;
+  readonly log: (event: string, data?: Record<string, unknown>) => void;
+}
+
+export interface DebugLoggerOptions {
+  /** Log whenever `__DEV__` is true, without the global filter. Defaults to false. */
+  readonly enabledInDev?: boolean;
+  /** Name of a legacy subsystem-specific global boolean, e.g. `"__T3_CLOUD_DEBUG__"`. */
+  readonly legacyGlobalFlag?: string;
+}
+
+function globalValue(name: string): unknown {
+  return typeof globalThis === "undefined"
+    ? undefined
+    : (globalThis as Record<string, unknown>)[name];
+}
+
+export function createDebugLogger(
+  namespace: string,
+  options: DebugLoggerOptions = {},
+): DebugLogger {
+  const isEnabled = () => {
+    if (options.enabledInDev === true && typeof __DEV__ !== "undefined" && __DEV__) {
+      return true;
+    }
+    if (options.legacyGlobalFlag !== undefined && globalValue(options.legacyGlobalFlag) === true) {
+      return true;
+    }
+    const filter = globalValue("__T3_DEBUG__");
+    return filter === true || (Array.isArray(filter) && filter.includes(namespace));
+  };
+  const log = (event: string, data?: Record<string, unknown>) => {
+    if (!isEnabled()) {
+      return;
+    }
+    if (data === undefined) {
+      console.log(`[t3-${namespace}] ${event}`);
+    } else {
+      console.log(`[t3-${namespace}] ${event}`, data);
+    }
+  };
+  return { isEnabled, log };
+}
diff --git a/apps/mobile/src/state/use-thread-outbox-drain.ts b/apps/mobile/src/state/use-thread-outbox-drain.ts
index 1147e9fd47af41cfb592a1c0d8d544705fcf8716..022c0ad6addbeda357185f771ab0fc5ed4fae561 100644
--- a/apps/mobile/src/state/use-thread-outbox-drain.ts
+++ b/apps/mobile/src/state/use-thread-outbox-drain.ts
@@ -17,6 +17,7 @@ import { AsyncResult } from "effect/unstable/reactivity";
 import { useCallback, useEffect, useRef, useState } from "react";
 import { Alert } from "react-native";
 
+import { createDebugLogger } from "../lib/debugLog";
 import { scopedThreadKey } from "../lib/scopedEntities";
 import { buildProjectThreadStartTurnInput } from "../lib/projectThreadStartTurn";
 import { serializeComposerMessageForServer, uploadedComposerContext } from "../lib/composerContext";
@@ -55,6 +56,7 @@ import {
   type QueuedThreadCreation,
   type QueuedThreadMessage,
   type ThreadOutboxCommandStage,
+  type ThreadOutboxFailureAction,
 } from "./thread-outbox-model";
 import { environmentThreadShells, threadEnvironment } from "./threads";
 import {
@@ -82,6 +84,92 @@ import {
   useRemoteConnectionStatus,
 } from "./use-remote-environment-registry";
 
+// Ordinary offline behavior (a socket dropping mid-request, a retryable
+// attachment upload failure) must not spam `console.warn` on every backoff
+// retry; it goes to the filterable `[t3-thread-outbox]` debug log instead.
+// Failures the server decided stay on `console.warn`.
+const threadOutboxDebug = createDebugLogger("thread-outbox");
+
+/**
+ * On the queued-request path (settings sync, startTurn) the RPC client
+ * reports ordinary transport drops as the raw socket/worker reason tags, and
+ * reserves `RpcClientDefect` for client-side protocol violations and decoding
+ * failures — unlike the shared config-subscription stream, which
+ * deliberately re-wraps transport causes under that tag. Defects still retry,
+ * but they are not ordinary offline behavior and must not hide behind the
+ * offline debug log.
+ */
+function isRpcClientDecodeDefect(error: unknown): boolean {
+  if (
+    typeof error !== "object" ||
+    error === null ||
+    !("_tag" in error) ||
+    error._tag !== "RpcClientError"
+  ) {
+    return false;
+  }
+  const reason: unknown = (error as { readonly reason?: unknown }).reason;
+  return (
+    typeof reason === "object" &&
+    reason !== null &&
+    "_tag" in reason &&
+    reason._tag === "RpcClientDefect"
+  );
+}
+
+function isOrdinaryThreadOutboxTransportFailure(error: unknown): boolean {
+  return shouldRetryThreadOutboxDelivery(error) && !isRpcClientDecodeDefect(error);
+}
+
+/**
+ * Logs one queued-message delivery failure and returns the retry-or-restore
+ * decision for the caller. Ordinary transport retries — what an offline
+ * device or a flapping socket produces on every backoff attempt — go to the
+ * debug log. Server-decided failures warn. Settings-sync failures always
+ * resolve to a retry even when the server rejected the command, so the
+ * error, not the resolved action, must decide the log level there; routing
+ * every retry to debug could hide a permanently rejected update forever.
+ */
+function logThreadOutboxDeliveryFailure(input: {
+  readonly stage: ThreadOutboxCommandStage;
+  readonly error: unknown;
+  readonly interrupted: boolean;
+  readonly context: Record<string, unknown>;
+}): ThreadOutboxFailureAction {
+  const action = resolveThreadOutboxFailureAction({
+    stage: input.stage,
+    error: input.error,
+    interrupted: input.interrupted,
+  });
+  const details = { ...input.context, stage: input.stage, action };
+  const ordinaryTransportRetry =
+    action === "retry" &&
+    !isRpcClientDecodeDefect(input.error) &&
+    (input.interrupted ||
+      input.stage !== "settings-sync" ||
+      shouldRetryThreadOutboxDelivery(input.error));
+  if (ordinaryTransportRetry) {
+    threadOutboxDebug.log("queued message delivery failed", details);
+  } else {
+    console.warn("[thread-outbox] queued message delivery failed", details);
+  }
+  return action;
+}
+
+/** Attachment uploads retry like delivery: transport failures are ordinary offline noise. */
+function logThreadOutboxUploadFailure(queuedMessage: QueuedThreadMessage, error: unknown): void {
+  const context = {
+    environmentId: queuedMessage.environmentId,
+    threadId: queuedMessage.threadId,
+    messageId: queuedMessage.messageId,
+  };
+  if (isOrdinaryThreadOutboxTransportFailure(error)) {
+    threadOutboxDebug.log("attachment upload failed; retrying", { ...context, error });
+  } else {
+    console.warn("[thread-outbox] failed to upload attachments", { ...context, error });
+  }
+}
+
 function beginDispatchingQueuedMessage(queuedMessageId: MessageId): void {
   appAtomRegistry.set(dispatchingQueuedMessageIdAtom, queuedMessageId);
 }
@@ -215,14 +303,13 @@ export async function completeQueuedMessageDelivery(
     );
     if (!removed) {
       forgetAcknowledgedThreadMessage(queuedMessage);
-      console.warn(
-        "[thread-outbox] delivered message was edited before cleanup; keeping the newer message",
-        {
-          environmentId: queuedMessage.environmentId,
-          threadId: queuedMessage.threadId,
-          messageId: queuedMessage.messageId,
-        },
-      );
+      // Losing the cleanup race to a user edit is an expected outcome the
+      // caller handles by keeping the newer message; it is not a warning.
+      threadOutboxDebug.log("delivered message was edited before cleanup", {
+        environmentId: queuedMessage.environmentId,
+        threadId: queuedMessage.threadId,
+        messageId: queuedMessage.messageId,
+      });
       return "edited";
     }
     return "removed";
@@ -667,18 +754,16 @@ export function useThreadOutboxDrain(): void {
         return null;
       }
       const error = Cause.squash(commandResult.cause);
-      const action = resolveThreadOutboxFailureAction({
+      const action = logThreadOutboxDeliveryFailure({
         stage,
         error,
         interrupted: Cause.hasInterruptsOnly(commandResult.cause),
-      });
-      console.warn("[thread-outbox] queued message delivery failed", {
-        environmentId: queuedMessage.environmentId,
-        threadId: queuedMessage.threadId,
-        messageId: queuedMessage.messageId,
-        stage,
-        cause: commandResult.cause,
-        action,
+        context: {
+          environmentId: queuedMessage.environmentId,
+          threadId: queuedMessage.threadId,
+          messageId: queuedMessage.messageId,
+          cause: commandResult.cause,
+        },
       });
       return {
         action,
@@ -772,7 +857,7 @@ export function useThreadOutboxDrain(): void {
           return true;
         }
       } catch (error) {
-        console.warn("[thread-outbox] failed to upload attachments", error);
+        logThreadOutboxUploadFailure(queuedMessage, error);
         if (!shouldRetryThreadOutboxDelivery(error)) {
           return restoreQueuedMessage(
             queuedMessage,
@@ -900,7 +985,7 @@ export function useThreadOutboxDrain(): void {
           return true;
         }
       } catch (error) {
-        console.warn("[thread-outbox] failed to upload attachments", error);
+        logThreadOutboxUploadFailure(queuedMessage, error);
         if (!shouldRetryThreadOutboxDelivery(error)) {
           return restoreQueuedMessage(
             queuedMessage,