feat(mcp): lint_url accepts real http(s) URLs via ChromiumDriver

crates/plumb-cli/tests/mcp_stdio.rs

@@ -130,7 +130,7 @@ fn mcp_initialize_and_tools_list() {
         .unwrap_or_else(|| panic!("lint_url tool missing: got {tools:?}"));
     assert_eq!(
         lint_url["description"],
-        "Lint a URL with Plumb. Walking-skeleton accepts plumb-fake:// URLs only."
+        "Lint a URL with Plumb. Accepts http(s):// and plumb-fake:// URLs."
     );
     assert_eq!(
         lint_url["inputSchema"]["properties"]["url"]["type"],

crates/plumb-mcp/AGENTS.md

@@ -45,7 +45,8 @@ Use the `09-mcp-tool-author` subagent for cookie-cutter execution.
 ## Depends on
 
 - `plumb-core` (types; `test-fake` feature enabled so `lint_url` can
-  serve the canned snapshot until the real CDP driver lands).
+  serve the canned snapshot for `plumb-fake://` URLs).
+- `plumb-cdp` (drives Chromium for real `http(s)://` URLs in `lint_url`).
 - `plumb-format` (mcp_compact).
 - `rmcp` (server + macros + transport-io + schemars features).
 - `tokio`, `serde`, `serde_json`, `schemars`, `thiserror`, `tracing`.

crates/plumb-mcp/Cargo.toml

@@ -14,8 +14,9 @@ keywords.workspace = true
 categories.workspace = true
 
 [dependencies]
-# `test-fake` is enabled so the walking-skeleton `lint_url` tool can
-# serve the canned snapshot until the real Chromium driver lands.
+# `test-fake` keeps the canned snapshot path available for
+# `plumb-fake://` URLs alongside the real Chromium driver path.
+plumb-cdp = { workspace = true }
 plumb-core = { workspace = true, features = ["test-fake"] }
 plumb-format = { workspace = true }
 rmcp = { workspace = true }

crates/plumb-mcp/src/lib.rs

@@ -7,8 +7,9 @@
 //!
 //! - `echo` — smoke-tests the transport.
 //! - `lint_url` — lints a URL and returns violations in the MCP-compact
-//!   shape from `docs/local/prd.md` §14.2. Walking-skeleton accepts
-//!   `plumb-fake://` URLs only.
+//!   shape from `docs/local/prd.md` §14.2. Accepts `http(s)://` URLs
+//!   (driven by `plumb_cdp::ChromiumDriver`) and `plumb-fake://` URLs
+//!   (served from the canned snapshot).
 //! - `explain_rule` — returns the canonical markdown documentation and
 //!   metadata for a built-in rule by id.
 //!
@@ -28,7 +29,8 @@ pub use explain::rule_ids as documented_rule_ids;
 
 use std::io;
 
-use plumb_core::{Config, PlumbSnapshot, register_builtin, run};
+use plumb_cdp::{BrowserDriver, ChromiumDriver, ChromiumOptions, Target, is_fake_url};
+use plumb_core::{Config, PlumbSnapshot, ViewportKey, register_builtin, run};
 use plumb_format::mcp_compact;
 use rmcp::{
     RoleServer, ServerHandler, ServiceExt,
@@ -67,7 +69,7 @@ pub struct EchoArgs {
 /// Arguments to the `lint_url` tool.
 #[derive(Debug, Deserialize, JsonSchema)]
 pub struct LintUrlArgs {
-    /// URL to lint. Walking-skeleton accepts `plumb-fake://` URLs only.
+    /// URL to lint. Accepts `http(s)://` and `plumb-fake://` URLs.
     pub url: String,
 }
 
@@ -96,12 +98,26 @@ impl PlumbServer {
     }
 
     async fn lint_url(&self, args: LintUrlArgs) -> Result<CallToolResult, ErrorData> {
-        if !args.url.starts_with("plumb-fake://") {
-            return Ok(CallToolResult::success(vec![Content::text(
-                "lint_url currently only accepts plumb-fake:// URLs in the walking skeleton.",
-            )]));
-        }
-        let snapshot = PlumbSnapshot::canned();
+        let snapshot = if is_fake_url(&args.url) {
+            PlumbSnapshot::canned()
+        } else {
+            let target = Target {
+                url: args.url.clone(),
+                viewport: ViewportKey::new("desktop"),
+                width: 1280,
+                height: 800,
+                device_pixel_ratio: 1.0,
+            };
+            let driver = ChromiumDriver::new(ChromiumOptions::default());
+            match driver.snapshot(target).await {
+                Ok(snap) => snap,
+                Err(err) => {
+                    return Ok(CallToolResult::error(vec![Content::text(format!(
+                        "lint_url failed: {err}"
+                    ))]));
+                }
+            }
+        };
         let config = Config::default();
         let violations = run(&snapshot, &config);
         let (text, structured) = mcp_compact(&violations);
@@ -202,7 +218,7 @@ impl ServerHandler for PlumbServer {
             tool_descriptor::<EchoArgs>("echo", "Echo a message — smoke test the MCP transport."),
             tool_descriptor::<LintUrlArgs>(
                 "lint_url",
-                "Lint a URL with Plumb. Walking-skeleton accepts plumb-fake:// URLs only.",
+                "Lint a URL with Plumb. Accepts http(s):// and plumb-fake:// URLs.",
             ),
             tool_descriptor::<ExplainRuleArgs>(
                 "explain_rule",

docs/src/mcp.md

@@ -32,12 +32,12 @@ For local development against a source checkout:
 }
 ```
 
-## Walking-skeleton tools
+## Tools
 
 | Tool | Description |
 |------|-------------|
 | `echo` | Smoke-test the transport. Echoes the `message` arg back. |
-| `lint_url` | Lint a URL. Accepts `plumb-fake://hello` only until the Chromium driver lands. |
+| `lint_url` | Lint a URL. Accepts `http(s)://` URLs (driven by the bundled Chromium driver) and `plumb-fake://hello` (canned snapshot for tests). On a Chromium launch failure the response is returned with `isError: true` and a single text block carrying the typed driver error. |
 | `explain_rule` | Return canonical documentation and metadata for a Plumb rule by id. Args: `{ "rule_id": "<category>/<id>" }`. |
 
 The response shape follows the MCP `content` + `structuredContent`