diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7633a36e2..d5dc9eae5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@
 - Agents: treat message tool errors as failures so fallback replies still send; require `to` + `message` for `action=send`. (#717) — thanks @theglove44.
 - Agents: route subagent transcripts to the target agent sessions directory and add regression coverage. (#708) — thanks @xMikeMickelson.
 - Agents/Tools: preserve action enums when flattening tool schemas. (#708) — thanks @xMikeMickelson.
+- Gateway/Agents: canonicalize main session aliases for store writes and add regression coverage. (#709) — thanks @xMikeMickelson.
 - Agents: reset sessions and retry when auto-compaction overflows instead of crashing the gateway.
 
 ## 2026.1.10
diff --git a/src/gateway/server-bridge.ts b/src/gateway/server-bridge.ts
index 55f7f1f22..fa3d616a5 100644
--- a/src/gateway/server-bridge.ts
+++ b/src/gateway/server-bridge.ts
@@ -24,7 +24,6 @@ import { buildConfigSchema } from "../config/schema.js";
 import {
   loadSessionStore,
   mergeSessionEntry,
-  resolveAgentMainSessionKey,
   resolveMainSessionKeyFromConfig,
   type SessionEntry,
   saveSessionStore,
@@ -36,10 +35,7 @@ import {
 } from "../infra/voicewake.js";
 import { clearCommandLane } from "../process/command-queue.js";
 import { normalizeProviderId } from "../providers/plugins/index.js";
-import {
-  normalizeMainKey,
-  resolveAgentIdFromSessionKey,
-} from "../routing/session-key.js";
+import { normalizeMainKey } from "../routing/session-key.js";
 import { defaultRuntime } from "../runtime.js";
 import {
   abortChatRunById,
@@ -93,6 +89,7 @@ import {
   readSessionMessages,
   resolveGatewaySessionStoreTarget,
   resolveSessionModelRef,
+  resolveSessionStoreKey,
   resolveSessionTranscriptCandidates,
   type SessionsPatchResult,
 } from "./session-utils.js";
@@ -922,12 +919,10 @@ export function createBridgeHandlers(ctx: BridgeHandlersContext) {
               clientRunId,
             });
 
-            // Normalize short main key alias to canonical form before store write
-            const agentId = resolveAgentIdFromSessionKey(p.sessionKey);
-            const mainSessionKey = resolveAgentMainSessionKey({ cfg, agentId });
-            const rawMainKey = normalizeMainKey(cfg.session?.mainKey);
-            const storeKey =
-              p.sessionKey === rawMainKey ? mainSessionKey : p.sessionKey;
+            const storeKey = resolveSessionStoreKey({
+              cfg,
+              sessionKey: p.sessionKey,
+            });
             if (store) {
               store[storeKey] = sessionEntry;
               if (storePath) {
@@ -1044,13 +1039,10 @@ export function createBridgeHandlers(ctx: BridgeHandlersContext) {
           typeof obj.sessionKey === "string" ? obj.sessionKey.trim() : "";
         const cfg = loadConfig();
         const rawMainKey = normalizeMainKey(cfg.session?.mainKey);
-        const sessionKey = sessionKeyRaw.length > 0 ? sessionKeyRaw : rawMainKey;
+        const sessionKey =
+          sessionKeyRaw.length > 0 ? sessionKeyRaw : rawMainKey;
         const { storePath, store, entry } = loadSessionEntry(sessionKey);
-        // Normalize short main key alias to canonical form before store write
-        const agentId = resolveAgentIdFromSessionKey(sessionKey);
-        const mainSessionKey = resolveAgentMainSessionKey({ cfg, agentId });
-        const storeKey =
-          sessionKey === rawMainKey ? mainSessionKey : sessionKey;
+        const storeKey = resolveSessionStoreKey({ cfg, sessionKey });
         const now = Date.now();
         const sessionId = entry?.sessionId ?? randomUUID();
         store[storeKey] = {
@@ -1128,16 +1120,11 @@ export function createBridgeHandlers(ctx: BridgeHandlersContext) {
         const sessionKey =
           sessionKeyRaw.length > 0 ? sessionKeyRaw : `node-${nodeId}`;
         const { storePath, store, entry } = loadSessionEntry(sessionKey);
-        // Normalize short main key alias to canonical form before store write
         const nodeCfg = loadConfig();
-        const nodeAgentId = resolveAgentIdFromSessionKey(sessionKey);
-        const nodeMainSessionKey = resolveAgentMainSessionKey({
+        const nodeStoreKey = resolveSessionStoreKey({
           cfg: nodeCfg,
-          agentId: nodeAgentId,
+          sessionKey,
         });
-        const nodeRawMainKey = normalizeMainKey(nodeCfg.session?.mainKey);
-        const nodeStoreKey =
-          sessionKey === nodeRawMainKey ? nodeMainSessionKey : sessionKey;
         const now = Date.now();
         const sessionId = entry?.sessionId ?? randomUUID();
         store[nodeStoreKey] = {
diff --git a/src/gateway/server-methods/agent.ts b/src/gateway/server-methods/agent.ts
index ce4e64b5f..ba1e633ae 100644
--- a/src/gateway/server-methods/agent.ts
+++ b/src/gateway/server-methods/agent.ts
@@ -11,7 +11,6 @@ import {
 import { registerAgentRunContext } from "../../infra/agent-events.js";
 import { resolveOutboundTarget } from "../../infra/outbound/targets.js";
 import { DEFAULT_CHAT_PROVIDER } from "../../providers/registry.js";
-import { normalizeMainKey } from "../../routing/session-key.js";
 import { defaultRuntime } from "../../runtime.js";
 import { resolveSendPolicy } from "../../sessions/send-policy.js";
 import {
@@ -29,7 +28,7 @@ import {
   validateAgentParams,
   validateAgentWaitParams,
 } from "../protocol/index.js";
-import { loadSessionEntry } from "../session-utils.js";
+import { loadSessionEntry, resolveSessionStoreKey } from "../session-utils.js";
 import { formatForLog } from "../ws-log.js";
 import { waitForAgentJob } from "./agent-job.js";
 import type { GatewayRequestHandlers } from "./types.js";
@@ -190,24 +189,21 @@ export const agentHandlers: GatewayRequestHandlers = {
         return;
       }
       resolvedSessionId = sessionId;
-      const agentId = resolveAgentIdFromSessionKey(requestedSessionKey);
-      const mainSessionKey = resolveAgentMainSessionKey({
+      const canonicalSessionKey = resolveSessionStoreKey({
         cfg,
-        agentId,
+        sessionKey: requestedSessionKey,
       });
-      const rawMainKey = normalizeMainKey(cfg.session?.mainKey);
-      // Normalize short main key alias to canonical form before store write
-      const storeKey =
-        requestedSessionKey === rawMainKey ? mainSessionKey : requestedSessionKey;
+      const agentId = resolveAgentIdFromSessionKey(canonicalSessionKey);
+      const mainSessionKey = resolveAgentMainSessionKey({ cfg, agentId });
       if (store) {
-        store[storeKey] = nextEntry;
+        store[canonicalSessionKey] = nextEntry;
         if (storePath) {
           await saveSessionStore(storePath, store);
         }
       }
       if (
-        requestedSessionKey === mainSessionKey ||
-        requestedSessionKey === rawMainKey
+        canonicalSessionKey === mainSessionKey ||
+        canonicalSessionKey === "global"
       ) {
         context.addChatRun(idem, {
           sessionKey: requestedSessionKey,
diff --git a/src/gateway/server-methods/chat.ts b/src/gateway/server-methods/chat.ts
index 3da182034..5f6ef9f6d 100644
--- a/src/gateway/server-methods/chat.ts
+++ b/src/gateway/server-methods/chat.ts
@@ -3,15 +3,7 @@ import { randomUUID } from "node:crypto";
 import { resolveThinkingDefault } from "../../agents/model-selection.js";
 import { resolveAgentTimeoutMs } from "../../agents/timeout.js";
 import { agentCommand } from "../../commands/agent.js";
-import {
-  mergeSessionEntry,
-  resolveAgentMainSessionKey,
-  saveSessionStore,
-} from "../../config/sessions.js";
-import {
-  normalizeMainKey,
-  resolveAgentIdFromSessionKey,
-} from "../../routing/session-key.js";
+import { mergeSessionEntry, saveSessionStore } from "../../config/sessions.js";
 import { registerAgentRunContext } from "../../infra/agent-events.js";
 import { defaultRuntime } from "../../runtime.js";
 import { resolveSendPolicy } from "../../sessions/send-policy.js";
@@ -40,6 +32,7 @@ import {
   loadSessionEntry,
   readSessionMessages,
   resolveSessionModelRef,
+  resolveSessionStoreKey,
 } from "../session-utils.js";
 import { formatForLog } from "../ws-log.js";
 import type { GatewayRequestHandlers } from "./types.js";
@@ -314,12 +307,10 @@ export const chatHandlers: GatewayRequestHandlers = {
         clientRunId,
       });
 
-      // Normalize short main key alias to canonical form before store write
-      const agentId = resolveAgentIdFromSessionKey(p.sessionKey);
-      const mainSessionKey = resolveAgentMainSessionKey({ cfg, agentId });
-      const rawMainKey = normalizeMainKey(cfg.session?.mainKey);
-      const storeKey =
-        p.sessionKey === rawMainKey ? mainSessionKey : p.sessionKey;
+      const storeKey = resolveSessionStoreKey({
+        cfg,
+        sessionKey: p.sessionKey,
+      });
       if (store) {
         store[storeKey] = sessionEntry;
         if (storePath) {
diff --git a/src/gateway/session-utils.test.ts b/src/gateway/session-utils.test.ts
index 9fa2cf36c..ce1afe8a6 100644
--- a/src/gateway/session-utils.test.ts
+++ b/src/gateway/session-utils.test.ts
@@ -1,9 +1,14 @@
+import os from "node:os";
+import path from "node:path";
 import { describe, expect, test } from "vitest";
+import type { ClawdbotConfig } from "../config/config.js";
 import type { SessionEntry } from "../config/sessions.js";
 import {
   capArrayByJsonBytes,
   classifySessionKey,
   parseGroupKey,
+  resolveGatewaySessionStoreTarget,
+  resolveSessionStoreKey,
 } from "./session-utils.js";
 
 describe("gateway session utils", () => {
@@ -31,4 +36,62 @@ describe("gateway session utils", () => {
     const entry = { chatType: "group" } as SessionEntry;
     expect(classifySessionKey("main", entry)).toBe("group");
   });
+
+  test("resolveSessionStoreKey maps main aliases to default agent main", () => {
+    const cfg = {
+      session: { mainKey: "work" },
+      agents: { list: [{ id: "ops", default: true }] },
+    } as ClawdbotConfig;
+    expect(resolveSessionStoreKey({ cfg, sessionKey: "main" })).toBe(
+      "agent:ops:work",
+    );
+    expect(resolveSessionStoreKey({ cfg, sessionKey: "work" })).toBe(
+      "agent:ops:work",
+    );
+  });
+
+  test("resolveSessionStoreKey canonicalizes bare keys to default agent", () => {
+    const cfg = {
+      session: { mainKey: "main" },
+      agents: { list: [{ id: "ops", default: true }] },
+    } as ClawdbotConfig;
+    expect(resolveSessionStoreKey({ cfg, sessionKey: "group:123" })).toBe(
+      "agent:ops:group:123",
+    );
+    expect(
+      resolveSessionStoreKey({ cfg, sessionKey: "agent:alpha:main" }),
+    ).toBe("agent:alpha:main");
+  });
+
+  test("resolveSessionStoreKey honors global scope", () => {
+    const cfg = {
+      session: { scope: "global", mainKey: "work" },
+      agents: { list: [{ id: "ops", default: true }] },
+    } as ClawdbotConfig;
+    expect(resolveSessionStoreKey({ cfg, sessionKey: "main" })).toBe("global");
+    const target = resolveGatewaySessionStoreTarget({ cfg, key: "main" });
+    expect(target.canonicalKey).toBe("global");
+    expect(target.agentId).toBe("ops");
+  });
+
+  test("resolveGatewaySessionStoreTarget uses canonical key for main alias", () => {
+    const storeTemplate = path.join(
+      os.tmpdir(),
+      "clawdbot-session-utils",
+      "{agentId}",
+      "sessions.json",
+    );
+    const cfg = {
+      session: { mainKey: "main", store: storeTemplate },
+      agents: { list: [{ id: "ops", default: true }] },
+    } as ClawdbotConfig;
+    const target = resolveGatewaySessionStoreTarget({ cfg, key: "main" });
+    expect(target.canonicalKey).toBe("agent:ops:main");
+    expect(target.storeKeys).toEqual(
+      expect.arrayContaining(["agent:ops:main", "main"]),
+    );
+    expect(target.storePath).toBe(
+      path.resolve(storeTemplate.replace("{agentId}", "ops")),
+    );
+  });
 });
diff --git a/src/gateway/session-utils.ts b/src/gateway/session-utils.ts
index aacd004f0..960ac9021 100644
--- a/src/gateway/session-utils.ts
+++ b/src/gateway/session-utils.ts
@@ -14,8 +14,7 @@ import { resolveStateDir } from "../config/paths.js";
 import {
   buildGroupDisplayName,
   loadSessionStore,
-  resolveAgentIdFromSessionKey,
-  resolveAgentMainSessionKey,
+  resolveMainSessionKey,
   resolveSessionTranscriptPath,
   resolveStorePath,
   type SessionEntry,
@@ -168,22 +167,18 @@ export function capArrayByJsonBytes<T>(
 export function loadSessionEntry(sessionKey: string) {
   const cfg = loadConfig();
   const sessionCfg = cfg.session;
-  const agentId = resolveAgentIdFromSessionKey(sessionKey);
+  const canonicalKey = resolveSessionStoreKey({ cfg, sessionKey });
+  const agentId = resolveSessionStoreAgentId(cfg, canonicalKey);
   const storePath = resolveStorePath(sessionCfg?.store, { agentId });
   const store = loadSessionStore(storePath);
-  const parsed = parseAgentSessionKey(sessionKey);
-  const legacyKey = parsed?.rest;
-  // Also try the canonical key if sessionKey is the short mainKey alias
-  const rawMainKey = normalizeMainKey(sessionCfg?.mainKey);
-  const canonicalKey =
-    sessionKey === rawMainKey
-      ? resolveAgentMainSessionKey({ cfg, agentId })
-      : undefined;
+  const parsed = parseAgentSessionKey(canonicalKey);
+  const legacyKey =
+    parsed?.rest ?? parseAgentSessionKey(sessionKey)?.rest ?? undefined;
   const entry =
+    store[canonicalKey] ??
     store[sessionKey] ??
-    (legacyKey ? store[legacyKey] : undefined) ??
-    (canonicalKey ? store[canonicalKey] : undefined);
-  return { cfg, storePath, store, entry };
+    (legacyKey ? store[legacyKey] : undefined);
+  return { cfg, storePath, store, entry, canonicalKey };
 }
 
 export function classifySessionKey(
@@ -293,6 +288,38 @@ function canonicalizeSessionKeyForAgent(agentId: string, key: string): string {
   return `agent:${normalizeAgentId(agentId)}:${key}`;
 }
 
+function resolveDefaultStoreAgentId(cfg: ClawdbotConfig): string {
+  return normalizeAgentId(resolveDefaultAgentId(cfg));
+}
+
+export function resolveSessionStoreKey(params: {
+  cfg: ClawdbotConfig;
+  sessionKey: string;
+}): string {
+  const raw = params.sessionKey.trim();
+  if (!raw) return raw;
+  if (raw === "global" || raw === "unknown") return raw;
+  const rawMainKey = normalizeMainKey(params.cfg.session?.mainKey);
+  if (raw === "main" || raw === rawMainKey) {
+    return resolveMainSessionKey(params.cfg);
+  }
+  if (raw.startsWith("agent:")) return raw;
+  const agentId = resolveDefaultStoreAgentId(params.cfg);
+  return canonicalizeSessionKeyForAgent(agentId, raw);
+}
+
+function resolveSessionStoreAgentId(
+  cfg: ClawdbotConfig,
+  canonicalKey: string,
+): string {
+  if (canonicalKey === "global" || canonicalKey === "unknown") {
+    return resolveDefaultStoreAgentId(cfg);
+  }
+  const parsed = parseAgentSessionKey(canonicalKey);
+  if (parsed?.agentId) return normalizeAgentId(parsed.agentId);
+  return resolveDefaultStoreAgentId(cfg);
+}
+
 function canonicalizeSpawnedByForAgent(
   agentId: string,
   spawnedBy?: string,
@@ -314,40 +341,29 @@ export function resolveGatewaySessionStoreTarget(params: {
   storeKeys: string[];
 } {
   const key = params.key.trim();
-  const agentId = resolveAgentIdFromSessionKey(key);
+  const canonicalKey = resolveSessionStoreKey({
+    cfg: params.cfg,
+    sessionKey: key,
+  });
+  const agentId = resolveSessionStoreAgentId(params.cfg, canonicalKey);
   const storeConfig = params.cfg.session?.store;
   const storePath = resolveStorePath(storeConfig, { agentId });
 
-  if (key === "global" || key === "unknown") {
-    return { agentId, storePath, canonicalKey: key, storeKeys: [key] };
+  if (canonicalKey === "global" || canonicalKey === "unknown") {
+    const storeKeys = key && key !== canonicalKey ? [canonicalKey, key] : [key];
+    return { agentId, storePath, canonicalKey, storeKeys };
   }
 
-  const parsed = parseAgentSessionKey(key);
-  if (parsed) {
-    return {
-      agentId,
-      storePath,
-      canonicalKey: key,
-      storeKeys: [key, parsed.rest],
-    };
-  }
-
-  if (key.startsWith("subagent:")) {
-    const canonical = canonicalizeSessionKeyForAgent(agentId, key);
-    return {
-      agentId,
-      storePath,
-      canonicalKey: canonical,
-      storeKeys: [canonical, key],
-    };
-  }
-
-  const canonical = canonicalizeSessionKeyForAgent(agentId, key);
+  const parsed = parseAgentSessionKey(canonicalKey);
+  const storeKeys = new Set<string>();
+  storeKeys.add(canonicalKey);
+  if (parsed?.rest) storeKeys.add(parsed.rest);
+  if (key && key !== canonicalKey) storeKeys.add(key);
   return {
     agentId,
     storePath,
-    canonicalKey: canonical,
-    storeKeys: [canonical, key],
+    canonicalKey,
+    storeKeys: Array.from(storeKeys),
   };
 }