diff --git a/packages/coding-agent/src/core/session-manager.ts b/packages/coding-agent/src/core/session-manager.ts
index feb177ad..b6edd96c 100644
--- a/packages/coding-agent/src/core/session-manager.ts
+++ b/packages/coding-agent/src/core/session-manager.ts
@@ -800,7 +800,7 @@ export class SessionManager {
 			if (this.fileEntries.length === 0) {
 				const explicitPath = this.sessionFile;
 				if (statSync(explicitPath).size > 0) {
-					throw new Error(`Session file is not a valid pi session and was not modified: ${explicitPath}`);
+					throw new Error(`Session file is not a valid pi session: ${explicitPath}`);
 				}
 				this.newSession();
 				this.sessionFile = explicitPath;
diff --git a/packages/coding-agent/test/session-file-invalid.test.ts b/packages/coding-agent/test/session-file-invalid.test.ts
index 47767b5f..c69ef43a 100644
--- a/packages/coding-agent/test/session-file-invalid.test.ts
+++ b/packages/coding-agent/test/session-file-invalid.test.ts
@@ -57,9 +57,7 @@ describe("--session invalid file handling", () => {
 		const result = await runCli(["--session", sessionFile, "-p", "hi"], projectDir, agentDir);
 
 		expect(result.code).toBe(1);
-		expect(result.stderr).toContain(
-			`Error: Session file is not a valid pi session and was not modified: ${sessionFile}`,
-		);
+		expect(result.stderr).toContain(`Error: Session file is not a valid pi session: ${sessionFile}`);
 		expect(result.stderr).not.toContain("SessionManager.open");
 		expect(result.stderr).not.toContain("at ");
 		expect(readFileSync(sessionFile, "utf8")).toBe(originalContent);
diff --git a/packages/coding-agent/test/session-manager/file-operations.test.ts b/packages/coding-agent/test/session-manager/file-operations.test.ts
index 379c73fd..d4ec0d2f 100644
--- a/packages/coding-agent/test/session-manager/file-operations.test.ts
+++ b/packages/coding-agent/test/session-manager/file-operations.test.ts
@@ -275,7 +275,7 @@ describe("SessionManager.setSessionFile with corrupted files", () => {
 		writeFileSync(noHeaderFile, originalContent);
 
 		expect(() => SessionManager.open(noHeaderFile, tempDir)).toThrow(
-			`Session file is not a valid pi session and was not modified: ${noHeaderFile}`,
+			`Session file is not a valid pi session: ${noHeaderFile}`,
 		);
 		expect(readFileSync(noHeaderFile, "utf-8")).toBe(originalContent);
 	});
@@ -286,7 +286,7 @@ describe("SessionManager.setSessionFile with corrupted files", () => {
 		writeFileSync(nonSessionFile, originalContent);
 
 		expect(() => SessionManager.open(nonSessionFile, tempDir)).toThrow(
-			`Session file is not a valid pi session and was not modified: ${nonSessionFile}`,
+			`Session file is not a valid pi session: ${nonSessionFile}`,
 		);
 		expect(readFileSync(nonSessionFile, "utf-8")).toBe(originalContent);
 	});