diff --git a/config/assertion-safety-baseline.txt b/config/assertion-safety-baseline.txt
index 94ec63b7eec7..85db3c053986 100644
--- a/config/assertion-safety-baseline.txt
+++ b/config/assertion-safety-baseline.txt
@@ -2714,7 +2714,7 @@ src/config/io.clobber-snapshot.ts	2
 src/config/io.context.ts	1
 src/config/io.health-state.ts	1
 src/config/io.invalid-config.ts	1
-src/config/io.load.ts	3
+src/config/io.load.ts	2
 src/config/io.observe-recovery.ts	11
 src/config/io.observe.ts	1
 src/config/io.read-helpers.ts	3
diff --git a/src/config/io.best-effort.test.ts b/src/config/io.best-effort.test.ts
index c1fa2e8a72a1..626f0da06cc4 100644
--- a/src/config/io.best-effort.test.ts
+++ b/src/config/io.best-effort.test.ts
@@ -227,6 +227,22 @@ describe("readBestEffortConfig", () => {
     });
   });
 
+  it("materializes fresh-install defaults when the config file is missing", async () => {
+    await withTempHome(async () => {
+      const { loadConfig } = await import("./io.runtime.js");
+
+      const snapshot = await readConfigFileSnapshot({ observe: false });
+      const loaded = loadConfig({ pin: false, skipPluginValidation: true });
+
+      expect(snapshot.exists).toBe(false);
+      // Missing config = fresh install; snapshot and load must produce the same
+      // out-of-box defaults an existing empty {} config gets (contextPruning
+      // stays provider-conditional, so compaction is the parity signal here).
+      expect(snapshot.config.agents?.defaults?.compaction?.mode).toBe("safeguard");
+      expect(loaded.agents?.defaults?.compaction?.mode).toBe("safeguard");
+    });
+  });
+
   it("reuses valid snapshots while preserving load-time defaults", async () => {
     await withTempHome(async (home) => {
       await writeOpenClawConfig(home, {
diff --git a/src/config/io.load.ts b/src/config/io.load.ts
index 7d406ad4f4b6..4252db4013c3 100644
--- a/src/config/io.load.ts
+++ b/src/config/io.load.ts
@@ -55,7 +55,15 @@ export function loadConfigFromContext(
           timeoutMs: resolveShellEnvFallbackTimeoutMs(deps.env),
         });
       }
-      return migratePersistedImplicitMainRoster({}).config as OpenClawConfig;
+      // A missing config is the fresh-install default path: materialize the
+      // same runtime defaults an empty {} config gets, or out-of-box behavior
+      // (compaction safeguard, session/cron defaults) silently diverges.
+      return materializeConfigForLoad(
+        context,
+        coerceConfig(migratePersistedImplicitMainRoster({}).config),
+        {},
+        undefined,
+      );
     }
     const raw = deps.fs.readFileSync(configPath, "utf-8");
     const parsed = deps.json5.parse(raw);
diff --git a/src/config/io.snapshot.ts b/src/config/io.snapshot.ts
index 9d1b675d30d6..f815aef433db 100644
--- a/src/config/io.snapshot.ts
+++ b/src/config/io.snapshot.ts
@@ -71,7 +71,13 @@ export async function readConfigFileSnapshotInternal(
         parsed: {},
         sourceConfig: config,
         valid: true,
-        runtimeConfig: config,
+        // Missing config is the fresh-install default path: materialize the
+        // same runtime defaults an existing empty {} config gets, so snapshot
+        // consumers see identical out-of-box behavior either way.
+        runtimeConfig: materializeRuntimeConfig(config, "snapshot", {
+          manifestRegistry:
+            context.options.pluginValidation === "core-only" ? { plugins: [] } : undefined,
+        }),
         hash: hashConfigRaw(null),
         issues: [],
         warnings: [],
diff --git a/src/config/materialize.ts b/src/config/materialize.ts
index c05e533d177b..22be388e05ff 100644
--- a/src/config/materialize.ts
+++ b/src/config/materialize.ts
@@ -16,36 +16,12 @@ import { normalizeExecSafeBinProfilesInConfig } from "./normalize-exec-safe-bin.
 import { normalizeConfigPaths } from "./normalize-paths.js";
 import type { OpenClawConfig, ResolvedSourceConfig, RuntimeConfig } from "./types.js";
 
-type ConfigMaterializationMode = "load" | "missing" | "snapshot";
-
-/** Defaults profile selected for config load, missing-file, or snapshot materialization. */
-type MaterializationProfile = {
-  includeCompactionDefaults: boolean;
-  includeContextPruningDefaults: boolean;
-  includeLoggingDefaults: boolean;
-  normalizePaths: boolean;
-};
-
 // Snapshot and load must materialize identically: prepared-runtime exact-config
 // resolution compares the startup-published (snapshot) config against the reply-path
 // (load) config, and any divergence permanently fails that resolve for affected configs.
-const FULL_MATERIALIZATION_PROFILE: MaterializationProfile = {
-  includeCompactionDefaults: true,
-  includeContextPruningDefaults: true,
-  includeLoggingDefaults: true,
-  normalizePaths: true,
-};
-
-const MATERIALIZATION_PROFILES: Record<ConfigMaterializationMode, MaterializationProfile> = {
-  load: FULL_MATERIALIZATION_PROFILE,
-  missing: {
-    includeCompactionDefaults: true,
-    includeContextPruningDefaults: true,
-    includeLoggingDefaults: false,
-    normalizePaths: false,
-  },
-  snapshot: FULL_MATERIALIZATION_PROFILE,
-};
+// The mode parameter documents the call site; a per-mode defaults profile existed
+// until its last divergent ("missing") caller was removed and only invited drift.
+type ConfigMaterializationMode = "load" | "snapshot";
 
 export function asResolvedSourceConfig(config: OpenClawConfig): ResolvedSourceConfig {
   return config as ResolvedSourceConfig;
@@ -57,34 +33,25 @@ export function asRuntimeConfig(config: OpenClawConfig): RuntimeConfig {
 
 export function materializeRuntimeConfig(
   config: OpenClawConfig,
-  mode: ConfigMaterializationMode,
+  _mode: ConfigMaterializationMode,
   options: {
     manifestRegistry?: Pick<PluginManifestRegistry, "plugins">;
     loadManifestRegistry?: () => Pick<PluginManifestRegistry, "plugins"> | undefined;
   } = {},
 ): RuntimeConfig {
-  const profile = MATERIALIZATION_PROFILES[mode];
   let next = applyMessageDefaults(config);
-  if (profile.includeLoggingDefaults) {
-    next = applyLoggingDefaults(next);
-  }
+  next = applyLoggingDefaults(next);
   next = applySessionDefaults(next);
   next = applyAgentDefaults(next);
   next = applyCronDefaults(next);
-  if (profile.includeContextPruningDefaults) {
-    next = applyContextPruningDefaults(next, { manifestRegistry: options.manifestRegistry });
-  }
-  if (profile.includeCompactionDefaults) {
-    next = applyCompactionDefaults(next);
-  }
+  next = applyContextPruningDefaults(next, { manifestRegistry: options.manifestRegistry });
+  next = applyCompactionDefaults(next);
   next = applyModelDefaults(next, {
     manifestRegistry: options.manifestRegistry,
     loadManifestRegistry: options.loadManifestRegistry,
   });
   next = applyTalkConfigNormalization(next);
-  if (profile.normalizePaths) {
-    normalizeConfigPaths(next);
-  }
+  normalizeConfigPaths(next);
   normalizeExecSafeBinProfilesInConfig(next);
   return asRuntimeConfig(inheritLegacyDefaultAgentId(config, next));
 }