diff --git a/CHANGELOG.md b/CHANGELOG.md
index 355cee7ad..86c881fd1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@ Docs: https://docs.clawd.bot
 
 ### Fixes
 - Config: avoid stack traces for invalid configs and log the config path.
+- Doctor: avoid recreating WhatsApp config when only legacy routing keys remain. (#900)
 - Doctor: warn when gateway.mode is unset with configure/config guidance.
 - OpenCode Zen: route models to the Zen API shape per family so proxy endpoints are used. (#1416)
 - macOS: include Textual syntax highlighting resources in packaged app to prevent chat crashes. (#1362)
diff --git a/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts b/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
index fd0f2f296..dbc08339d 100644
--- a/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
+++ b/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
@@ -23,21 +23,33 @@ describe("legacy config detection", () => {
       expect(res.issues[0]?.path).toBe("routing.groupChat.requireMention");
     }
   });
-  it("migrates routing.allowFrom to channels.whatsapp.allowFrom", async () => {
+  it("migrates routing.allowFrom to channels.whatsapp.allowFrom when whatsapp configured", async () => {
     vi.resetModules();
     const { migrateLegacyConfig } = await import("./config.js");
     const res = migrateLegacyConfig({
       routing: { allowFrom: ["+15555550123"] },
+      channels: { whatsapp: {} },
     });
     expect(res.changes).toContain("Moved routing.allowFrom → channels.whatsapp.allowFrom.");
     expect(res.config?.channels?.whatsapp?.allowFrom).toEqual(["+15555550123"]);
     expect(res.config?.routing?.allowFrom).toBeUndefined();
   });
-  it("migrates routing.groupChat.requireMention to channels whatsapp/telegram/imessage groups", async () => {
+  it("drops routing.allowFrom when whatsapp missing", async () => {
+    vi.resetModules();
+    const { migrateLegacyConfig } = await import("./config.js");
+    const res = migrateLegacyConfig({
+      routing: { allowFrom: ["+15555550123"] },
+    });
+    expect(res.changes).toContain("Removed routing.allowFrom (channels.whatsapp not configured).");
+    expect(res.config?.channels?.whatsapp).toBeUndefined();
+    expect(res.config?.routing?.allowFrom).toBeUndefined();
+  });
+  it("migrates routing.groupChat.requireMention to channels whatsapp/telegram/imessage groups when whatsapp configured", async () => {
     vi.resetModules();
     const { migrateLegacyConfig } = await import("./config.js");
     const res = migrateLegacyConfig({
       routing: { groupChat: { requireMention: false } },
+      channels: { whatsapp: {} },
     });
     expect(res.changes).toContain(
       'Moved routing.groupChat.requireMention → channels.whatsapp.groups."*".requireMention.',
@@ -53,6 +65,26 @@ describe("legacy config detection", () => {
     expect(res.config?.channels?.imessage?.groups?.["*"]?.requireMention).toBe(false);
     expect(res.config?.routing?.groupChat?.requireMention).toBeUndefined();
   });
+  it("migrates routing.groupChat.requireMention to telegram/imessage when whatsapp missing", async () => {
+    vi.resetModules();
+    const { migrateLegacyConfig } = await import("./config.js");
+    const res = migrateLegacyConfig({
+      routing: { groupChat: { requireMention: false } },
+    });
+    expect(res.changes).toContain(
+      'Moved routing.groupChat.requireMention → channels.telegram.groups."*".requireMention.',
+    );
+    expect(res.changes).toContain(
+      'Moved routing.groupChat.requireMention → channels.imessage.groups."*".requireMention.',
+    );
+    expect(res.changes).not.toContain(
+      'Moved routing.groupChat.requireMention → channels.whatsapp.groups."*".requireMention.',
+    );
+    expect(res.config?.channels?.whatsapp).toBeUndefined();
+    expect(res.config?.channels?.telegram?.groups?.["*"]?.requireMention).toBe(false);
+    expect(res.config?.channels?.imessage?.groups?.["*"]?.requireMention).toBe(false);
+    expect(res.config?.routing?.groupChat?.requireMention).toBeUndefined();
+  });
   it("migrates routing.groupChat.mentionPatterns to messages.groupChat.mentionPatterns", async () => {
     vi.resetModules();
     const { migrateLegacyConfig } = await import("./config.js");
diff --git a/src/config/legacy.migrations.part-1.ts b/src/config/legacy.migrations.part-1.ts
index d1d0a57e7..f537c3ce8 100644
--- a/src/config/legacy.migrations.part-1.ts
+++ b/src/config/legacy.migrations.part-1.ts
@@ -156,11 +156,16 @@ export const LEGACY_CONFIG_MIGRATIONS_PART_1: LegacyConfigMigration[] = [
       const allowFrom = (routing as Record<string, unknown>).allowFrom;
       if (allowFrom === undefined) return;
 
-      const channels = ensureRecord(raw, "channels");
-      const whatsapp =
-        channels.whatsapp && typeof channels.whatsapp === "object"
-          ? (channels.whatsapp as Record<string, unknown>)
-          : {};
+      const channels = getRecord(raw.channels);
+      const whatsapp = channels ? getRecord(channels.whatsapp) : null;
+      if (!whatsapp) {
+        delete (routing as Record<string, unknown>).allowFrom;
+        if (Object.keys(routing as Record<string, unknown>).length === 0) {
+          delete raw.routing;
+        }
+        changes.push("Removed routing.allowFrom (channels.whatsapp not configured).");
+        return;
+      }
 
       if (whatsapp.allowFrom === undefined) {
         whatsapp.allowFrom = allowFrom;
@@ -173,8 +178,8 @@ export const LEGACY_CONFIG_MIGRATIONS_PART_1: LegacyConfigMigration[] = [
       if (Object.keys(routing as Record<string, unknown>).length === 0) {
         delete raw.routing;
       }
-      channels.whatsapp = whatsapp;
-      raw.channels = channels;
+      channels!.whatsapp = whatsapp;
+      raw.channels = channels!;
     },
   },
   {
@@ -193,7 +198,11 @@ export const LEGACY_CONFIG_MIGRATIONS_PART_1: LegacyConfigMigration[] = [
       if (requireMention === undefined) return;
 
       const channels = ensureRecord(raw, "channels");
-      const applyTo = (key: "whatsapp" | "telegram" | "imessage") => {
+      const applyTo = (
+        key: "whatsapp" | "telegram" | "imessage",
+        options?: { requireExisting?: boolean },
+      ) => {
+        if (options?.requireExisting && !isRecord(channels[key])) return;
         const section =
           channels[key] && typeof channels[key] === "object"
             ? (channels[key] as Record<string, unknown>)
@@ -222,7 +231,7 @@ export const LEGACY_CONFIG_MIGRATIONS_PART_1: LegacyConfigMigration[] = [
         }
       };
 
-      applyTo("whatsapp");
+      applyTo("whatsapp", { requireExisting: true });
       applyTo("telegram");
       applyTo("imessage");