Implement URL.parse and URL.canParse for Code OSS browser consumers

[wieslawsoltes]

Merged implementation checkpoint — 20 September 2026

Exact heads: WebScene main 5e24b469e28cd19259a2853fa44a45fa02bbfb45, AppScene main 773e94e26b58eac423ca24d5e47bea172965c94c, unchanged Code OSS 645f29cc3176500b4b5762ba887cf2a7f0ffdf2c, local vscode-demo 2e6012d520ede98126777ffebffe86aef1780f8a (clean, 305 commits ahead, intentionally unpushed), WebScene consolidation #76 29ba147ef83fceb6c981d94698e29e7619417fce, and AppScene consolidation #65 0702d52e37d0a1aeeac6956092c5b241a9c05beb. Repository Actions remain disabled.

PR #769 merged at WebScene main 5e24b469e28cd19259a2853fa44a45fa02bbfb45. Implementation commit 24c18362906da7314eeda6e1af12f7eafb7afad5 adds allocation-bounded URL.parse() and URL.canParse() in main and iframe realms for unchanged Browser View, Chat, MCP, agent-session, and session-artifact consumers. Ledger commit 01b980bbf32c331ad691ed8d8ac5930f7441d827 records the scope.

Native/browser gates were authored but not executed. The enclosing URL parser remains explicitly partial, and exact-package consumer acceptance stays under #260/#261/#263/#264.

Parent capability ledger: #263
Product consumers: #260 and #261
Webview/browser surface: #264

Proven gap

Unchanged Code OSS 1.137 directly calls URL.parse() and URL.canParse() in browser-reachable Browser View, Chat question validation, MCP elicitation, agent-session input, and session-artifact paths. WebScene's main and iframe WebSceneURL classes currently expose only the constructor plus object-URL helpers, so these calls fail with a missing-function TypeError.

Representative unchanged sources include:

• src/vs/workbench/contrib/browserView/common/browserView.ts
• src/vs/workbench/contrib/mcp/browser/mcpElicitationService.ts
• src/vs/workbench/contrib/chat/common/chatService/chatQuestionCarouselHelpers.ts
• src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostSessionInputPills.ts
• src/vs/sessions/contrib/chat/browser/sessionArtifacts.ts

Focused implementation

• Add browser-shaped URL.canParse(url, base?) and URL.parse(url, base?) static methods in main and iframe realms.
• Require the URL argument, convert inputs consistently, accept absolute supported schemes, allow relative input only with a valid absolute base, reject invalid special-scheme authorities, and return null from parse for parse failure.
• Keep object-URL behavior and unchanged Code OSS intact.
• Add bounded native/browser contracts for method shape, absolute/relative inputs, invalid inputs, special and non-special schemes, optional bases, main/iframe parity, and conversion failures.

The current URL constructor remains a deliberately partial parser; this issue closes the missing static consumer surface without claiming full WHATWG URL conformance.

Deferred acceptance

Focused gates are authored with the implementation. Execution and exact-package Browser View, Chat, MCP, and session-artifact acceptance remain under #263/#260/#261/#264 and the active throughput directive.