Don't flatten SSH failures into empty results

Remote methods (readRemoteFile, listSessionIds, getRemoteDirectorySize)
now distinguish expected not-found/permission errors from unexpected
SSH transport/auth failures. Unexpected failures are logged with
logger.warn and reported to Sentry via captureException, preventing
silent degradation where auth regressions appear as 'no sessions'.

Author: nolanmclark

src/main/storage/copilot-session-storage.ts

@@ -451,12 +451,35 @@ export class CopilotSessionStorage extends BaseSessionStorage {
 		}
 	}
 
+	/** Check if a remote-fs error indicates a benign not-found/permission case vs an unexpected SSH failure. */
+	private isExpectedRemoteError(error?: string): boolean {
+		if (!error) return false;
+		const lower = error.toLowerCase();
+		return (
+			lower.includes('not found') ||
+			lower.includes('not accessible') ||
+			lower.includes('no such file') ||
+			lower.includes('permission denied') ||
+			lower.includes('does not exist')
+		);
+	}
+
 	/** List all session directory names from the session state directory. */
 	private async listSessionIds(sshConfig?: SshRemoteConfig): Promise<string[]> {
 		const sessionStateDir = this.getSessionStateDir(sshConfig);
 		if (sshConfig) {
 			const result = await readDirRemote(sessionStateDir, sshConfig);
 			if (!result.success || !result.data) {
+				if (!this.isExpectedRemoteError(result.error)) {
+					logger.warn(
+						`Unexpected SSH failure listing Copilot sessions: ${result.error}`,
+						LOG_CONTEXT
+					);
+					captureException(new Error(result.error || 'readDirRemote failed'), {
+						operation: 'copilotStorage:listSessionIds:remote',
+						sessionStateDir,
+					});
+				}
 				return [];
 			}
 			return result.data.filter((entry) => entry.isDirectory).map((entry) => entry.name);
@@ -590,21 +613,37 @@ export class CopilotSessionStorage extends BaseSessionStorage {
 		}
 	}
 
-	/** Read a file from a remote host via SSH. Returns null on failure. */
+	/** Read a file from a remote host via SSH. Returns null on not-found; reports unexpected failures to Sentry. */
 	private async readRemoteFile(
 		filePath: string,
 		sshConfig: SshRemoteConfig
 	): Promise<string | null> {
 		const result = await readFileRemote(filePath, sshConfig);
-		return result.success && result.data ? result.data : null;
+		if (result.success && result.data) return result.data;
+		if (!this.isExpectedRemoteError(result.error)) {
+			logger.warn(`Unexpected SSH failure reading ${filePath}: ${result.error}`, LOG_CONTEXT);
+			captureException(new Error(result.error || 'readFileRemote failed'), {
+				operation: 'copilotStorage:readRemoteFile',
+				filePath,
+			});
+		}
+		return null;
 	}
 
-	/** Calculate the total size of a session directory on a remote host. */
+	/** Calculate the total size of a session directory on a remote host. Returns 0 on not-found; reports unexpected failures. */
 	private async getRemoteDirectorySize(
 		sessionDir: string,
 		sshConfig: SshRemoteConfig
 	): Promise<number> {
 		const result = await directorySizeRemote(sessionDir, sshConfig);
-		return result.success && result.data ? result.data : 0;
+		if (result.success && result.data) return result.data;
+		if (!this.isExpectedRemoteError(result.error)) {
+			logger.warn(`Unexpected SSH failure sizing ${sessionDir}: ${result.error}`, LOG_CONTEXT);
+			captureException(new Error(result.error || 'directorySizeRemote failed'), {
+				operation: 'copilotStorage:getRemoteDirectorySize',
+				sessionDir,
+			});
+		}
+		return 0;
 	}
 }