diff --git a/packages/tools/src/claude-memory.test.ts b/packages/tools/src/claude-memory.test.ts
index c4f62f16c..d5abbba12 100644
--- a/packages/tools/src/claude-memory.test.ts
+++ b/packages/tools/src/claude-memory.test.ts
@@ -16,7 +16,7 @@ vi.mock("supermemory", () => {
 	}
 })
 
-import { ClaudeMemoryTool } from "./claude-memory"
+import { ClaudeMemoryTool, pathToCustomId } from "./claude-memory"
 
 const FILE_PATH = "/memories/notes.txt"
 // 5 distinct lines so an off-by-one at either end is observable.
@@ -181,3 +181,38 @@ describe("ClaudeMemoryTool str_replace replacement literalness", () => {
 		expect(stored).not.toContain("line3")
 	})
 })
+
+describe("pathToCustomId", () => {
+	it("keeps the legacy flattening for canonical single-segment paths", () => {
+		// Backward compatibility: documents already stored under the legacy id
+		// (no underscores, one dot, one slash) must keep resolving.
+		expect(pathToCustomId("/memories/file.txt")).toBe("memories_file_txt")
+		expect(pathToCustomId("/projects/spec.md")).toBe("projects_spec_md")
+		// Shapes outside the canonical /dir/file.ext form are digested even
+		// when they look flattenable.
+		expect(pathToCustomId("notes.txt")).toBe("notes_txt_e39538e7")
+	})
+
+	it("disambiguates paths that would collide under plain flattening", () => {
+		// "notes.txt", "notes_txt", and "notes/txt" all flattened to the same
+		// id, so one file could silently overwrite another (#1547).
+		const a = pathToCustomId("/memories/notes.txt")
+		const b = pathToCustomId("/memories/notes_txt")
+		const c = pathToCustomId("/memories/notes/txt")
+
+		expect(new Set([a, b, c]).size).toBe(3)
+		for (const id of [a, b, c]) {
+			expect(id.startsWith("memories_notes_txt")).toBe(true)
+		}
+	})
+
+	it("is deterministic for the same input", () => {
+		expect(pathToCustomId("/memories/my_notes/v1.txt")).toBe(
+			pathToCustomId("/memories/my_notes/v1.txt"),
+		)
+	})
+
+	it("differs for distinct underscore paths sharing a flattening", () => {
+		expect(pathToCustomId("/a_b/c.txt")).not.toBe(pathToCustomId("/a/b_c.txt"))
+	})
+})
diff --git a/packages/tools/src/claude-memory.ts b/packages/tools/src/claude-memory.ts
index 8c665701a..989c9b58a 100644
--- a/packages/tools/src/claude-memory.ts
+++ b/packages/tools/src/claude-memory.ts
@@ -1,3 +1,4 @@
+import { createHash } from "node:crypto"
 import Supermemory from "supermemory"
 import { getContainerTags } from "./tools-shared"
 import type { SupermemoryToolsConfig } from "./types"
@@ -37,6 +38,33 @@ export interface MemoryToolResult {
 	is_error: boolean
 }
 
+/**
+ * Normalize a memory file path to the customId used for document identity.
+ *
+ * Paths in the canonical single-segment shape (`/memories/file.txt`: no
+ * underscores, exactly one dot, exactly one slash) keep the exact legacy id,
+ * so documents already stored under it continue to resolve.
+ *
+ * Plain flattening is otherwise non-injective — `notes.txt`, `notes_txt`,
+ * and `notes/txt` all collapse to the same id, so creating one file could
+ * silently overwrite another (#1547). Every other shape therefore gets a
+ * short digest of the original path appended, making distinct paths map to
+ * distinct ids again.
+ */
+export function pathToCustomId(path: string): string {
+	const stripped = path.replace(/^\//, "")
+	const legacyCompatible =
+		!stripped.includes("_") &&
+		stripped.split(".").length === 2 &&
+		stripped.split("/").length === 2
+	if (legacyCompatible) {
+		return stripped.replace(/\//g, "_").replace(/\./g, "_")
+	}
+	const flattened = stripped.replace(/\//g, "_").replace(/\./g, "_")
+	const digest = createHash("sha256").update(stripped).digest("hex").slice(0, 8)
+	return `${flattened}_${digest}`
+}
+
 /**
  * Claude Memory Tool - Client-side implementation
  * Maps Claude's memory tool commands to supermemory document operations
@@ -51,10 +79,7 @@ export class ClaudeMemoryTool {
 	 * Converts /memories/file.txt -> memories_file_txt
 	 */
 	private normalizePathToCustomId(path: string): string {
-		return path
-			.replace(/^\//, "") // Remove leading slash
-			.replace(/\//g, "_") // Replace / with _
-			.replace(/\./g, "_") // Replace . with _
+		return pathToCustomId(path)
 	}
 
 	constructor(apiKey: string, config?: ClaudeMemoryConfig) {