fix: address Copilot review — add link range assertions & extract settings hint helper

- Add startIndex/length assertions to all 4 underline-wrapped link tests
  to verify visual and interactive boundaries stay aligned (LOW-1)
- Extract private writeSettingsHintLine() to deduplicate the settings hint
  formatting pattern in DocumentDBShellPty (INFO-1)

Author: tnaum-ms

src/documentdb/shell/DocumentDBShellPty.ts

@@ -535,10 +535,7 @@ export class DocumentDBShellPty implements vscode.Pseudoterminal {
 
             // Show a hint line and clickable settings link for errors that reference a VS Code setting
             if (error instanceof SettingsHintError) {
-                const settingsLink = this._outputFormatter.formatLinkSentinel(
-                    `${SETTINGS_ACTION_PREFIX}[${error.settingKey}]`,
-                );
-                this.writeLine(this._outputFormatter.formatSystemMessage(`${error.settingsHint} ${settingsLink}`));
+                this.writeSettingsHintLine(error);
             }
 
             this._inputHandler.setEnabled(true);
@@ -690,10 +687,7 @@ export class DocumentDBShellPty implements vscode.Pseudoterminal {
 
         // Show a hint line and clickable settings link for errors that reference a VS Code setting
         if (error instanceof SettingsHintError) {
-            const settingsLink = this._outputFormatter.formatLinkSentinel(
-                `${SETTINGS_ACTION_PREFIX}[${error.settingKey}]`,
-            );
-            this.writeLine(this._outputFormatter.formatSystemMessage(`${error.settingsHint} ${settingsLink}`));
+            this.writeSettingsHintLine(error);
         }
 
         // Detect query timeout errors (error code 50: MaxTimeMSExpired / ExceededTimeLimit)
@@ -865,6 +859,14 @@ export class DocumentDBShellPty implements vscode.Pseudoterminal {
 
     // ─── Private: Action line ("Open in Collection View") ────────────────────
 
+    /**
+     * Write a hint line with a clickable settings link for a {@link SettingsHintError}.
+     */
+    private writeSettingsHintLine(error: SettingsHintError): void {
+        const settingsLink = this._outputFormatter.formatLinkSentinel(`${SETTINGS_ACTION_PREFIX}[${error.settingKey}]`);
+        this.writeLine(this._outputFormatter.formatSystemMessage(`${error.settingsHint} ${settingsLink}`));
+    }
+
     /**
      * If the result came from a query with a known namespace (db + collection),
      * write clickable action lines below the output.

src/documentdb/shell/ShellTerminalLinkProvider.test.ts

@@ -176,6 +176,8 @@ describe('ShellTerminalLinkProvider', () => {
             expect(links).toHaveLength(1);
             expect(links[0]).toMatchObject({
                 linkType: 'collectionView',
+                startIndex: 0,
+                length: actionLine.length,
                 databaseName: 'mydb',
                 collectionName: 'users',
             });
@@ -195,6 +197,8 @@ describe('ShellTerminalLinkProvider', () => {
             expect(links).toHaveLength(1);
             expect(links[0]).toMatchObject({
                 linkType: 'collectionView',
+                startIndex: 0,
+                length: actionLine.length,
                 databaseName: 'mydb',
                 collectionName: 'users',
             });
@@ -294,6 +298,8 @@ describe('ShellTerminalLinkProvider', () => {
             expect(links).toHaveLength(1);
             expect(links[0]).toMatchObject({
                 linkType: 'settings',
+                startIndex: 0,
+                length: actionLine.length,
                 settingKey: 'documentDB.shell.initTimeout',
             });
         });
@@ -377,10 +383,9 @@ describe('ShellTerminalLinkProvider', () => {
             registerShellTerminal(mockTerminal, () => mockShellInfo('test-cluster-id'));
 
             // Matches real output: gray wraps the whole line, each link segment is underlined separately
-            const actionLine =
-                `\x1b[90m\x1b[4m${ACTION_LINE_PREFIX}[mydb.orders]\x1b[24m` +
-                `  ` +
-                `\x1b[4m${PLAYGROUND_ACTION_PREFIX}[mydb.orders]\x1b[24m\x1b[0m`;
+            const collectionPart = `\x1b[90m\x1b[4m${ACTION_LINE_PREFIX}[mydb.orders]\x1b[24m`;
+            const playgroundPart = `\x1b[4m${PLAYGROUND_ACTION_PREFIX}[mydb.orders]\x1b[24m\x1b[0m`;
+            const actionLine = `${collectionPart}  ${playgroundPart}`;
             const context = {
                 terminal: mockTerminal,
                 line: actionLine,
@@ -390,11 +395,15 @@ describe('ShellTerminalLinkProvider', () => {
             expect(links).toHaveLength(2);
             expect(links[0]).toMatchObject({
                 linkType: 'collectionView',
+                startIndex: 0,
+                length: collectionPart.length,
                 databaseName: 'mydb',
                 collectionName: 'orders',
             });
             expect(links[1]).toMatchObject({
                 linkType: 'playground',
+                startIndex: collectionPart.length + 2, // +2 for "  " separator
+                length: playgroundPart.length,
                 databaseName: 'mydb',
                 collectionName: 'orders',
             });