diff --git a/packages/opencode/src/project/project.ts b/packages/opencode/src/project/project.ts
index f4b8b940d20..f36881d4a3a 100644
--- a/packages/opencode/src/project/project.ts
+++ b/packages/opencode/src/project/project.ts
@@ -14,6 +14,7 @@ import { NodeFileSystem, NodePath } from "@effect/platform-node"
 import { makeRuntime } from "@/effect/run-service"
 import { AppFileSystem } from "@/filesystem"
 import * as CrossSpawnSpawner from "@/effect/cross-spawn-spawner"
+import { Filesystem } from "@/util/filesystem"
 
 export namespace Project {
   const log = Log.create({ service: "project" })
@@ -315,7 +316,7 @@ export namespace Project {
             d
               .update(SessionTable)
               .set({ project_id: data.id })
-              .where(and(eq(SessionTable.project_id, ProjectID.global), eq(SessionTable.directory, data.worktree)))
+              .where(and(eq(SessionTable.project_id, ProjectID.global), eq(SessionTable.directory, Filesystem.normalizePathSeparators(data.worktree))))
               .run(),
           )
         }
diff --git a/packages/opencode/src/session/index.ts b/packages/opencode/src/session/index.ts
index eb01739c156..5deeb84a460 100644
--- a/packages/opencode/src/session/index.ts
+++ b/packages/opencode/src/session/index.ts
@@ -17,6 +17,7 @@ import { ProjectTable } from "../project/project.sql"
 import { Storage } from "@/storage/storage"
 import { Log } from "../util/log"
 import { updateSchema } from "../util/update-schema"
+import { Filesystem } from "@/util/filesystem"
 import { MessageV2 } from "./message-v2"
 import { Instance } from "../project/instance"
 import { SessionPrompt } from "./prompt"
@@ -400,7 +401,7 @@ export namespace Session {
           slug: Slug.create(),
           version: Installation.VERSION,
           projectID: Instance.project.id,
-          directory: input.directory,
+          directory: Filesystem.normalizePathSeparators(input.directory),
           workspaceID: input.workspaceID,
           parentID: input.parentID,
           title: input.title ?? createDefaultTitle(!!input.parentID),
@@ -768,7 +769,7 @@ export namespace Session {
       conditions.push(eq(SessionTable.workspace_id, input.workspaceID))
     }
     if (input?.directory) {
-      conditions.push(eq(SessionTable.directory, input.directory))
+      conditions.push(eq(SessionTable.directory, Filesystem.normalizePathSeparators(input.directory)))
     }
     if (input?.roots) {
       conditions.push(isNull(SessionTable.parent_id))
@@ -808,7 +809,7 @@ export namespace Session {
     const conditions: SQL[] = []
 
     if (input?.directory) {
-      conditions.push(eq(SessionTable.directory, input.directory))
+      conditions.push(eq(SessionTable.directory, Filesystem.normalizePathSeparators(input.directory)))
     }
     if (input?.roots) {
       conditions.push(isNull(SessionTable.parent_id))
diff --git a/packages/opencode/src/util/filesystem.ts b/packages/opencode/src/util/filesystem.ts
index 37f00c6b9c8..fdccb5b498b 100644
--- a/packages/opencode/src/util/filesystem.ts
+++ b/packages/opencode/src/util/filesystem.ts
@@ -113,6 +113,23 @@ export namespace Filesystem {
     }
   }
 
+  /**
+   * Normalize path separators to forward slashes for consistent database queries.
+   * This fixes Windows path compatibility issues where paths might use backslashes
+   * in some cases and forward slashes in others, and ensures consistent drive letter casing.
+   */
+  export function normalizePathSeparators(p: string): string {
+    // Convert backslashes to forward slashes
+    let normalized = p.replace(/\\/g, "/")
+
+    // Normalize Windows drive letters to uppercase (e.g., c:/ -> C:/)
+    if (/^[a-z]:\//.test(normalized)) {
+      normalized = normalized[0].toUpperCase() + normalized.slice(1)
+    }
+
+    return normalized
+  }
+
   // We cannot rely on path.resolve() here because git.exe may come from Git Bash, Cygwin, or MSYS2, so we need to translate these paths at the boundary.
   // Also resolves symlinks so that callers using the result as a cache key
   // always get the same canonical path for a given physical directory.