feat(amazonq): added dev override for registry URL (#8326)

## Problem

Developers need a way to override the MCP registry URL for testing and
development purposes without modifying production code or waiting for
backend profile configuration changes. Currently, the registry URL is
only fetched from the `getProfile` API call, making it difficult to test
against different registry endpoints during development.

## Solution

Added a new developer setting `aws.dev.amazonqRegistry` with a
`registryUrl` field that allows overriding the MCP registry URL from
VSCode settings. The override takes precedence over the URL fetched from
`getProfile`, enabling developers to easily test against custom registry
endpoints.

**Changes:**
- **VSCode Extension**: Added `amazonqRegistry` to dev settings,
extracted `registryUrl` from config, and passed it to the language
server via initialization options
- **Language Server**: Added `registryUrl` to client capabilities,
updated `ProfileStatusMonitor` to accept and prioritize override URL,
and modified `McpToolsServer` to use the override when initializing MCP
Manager

**Usage:**
```json
{
    "aws.dev.amazonqRegistry": {
        "registryUrl": "https://custom-registry.example.com/manifest.json"
    }
}
```

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: ashishrp-aws

packages/amazonq/src/lsp/activation.ts

@@ -7,19 +7,29 @@ import vscode from 'vscode'
 import { startLanguageServer } from './client'
 import { AmazonQLspInstaller, getBundledResourcePaths } from './lspInstaller'
 import { lspSetupStage, ToolkitError, messages, getLogger } from 'aws-core-vscode/shared'
+import { getAmazonQLspConfig } from './config'
 
 export async function activate(ctx: vscode.ExtensionContext): Promise<void> {
+    const config = getAmazonQLspConfig()
+    const registryUrl = config.registryUrl
+
     try {
         await lspSetupStage('all', async () => {
             const installResult = await new AmazonQLspInstaller().resolve()
-            await lspSetupStage('launch', async () => await startLanguageServer(ctx, installResult.resourcePaths))
+            await lspSetupStage(
+                'launch',
+                async () => await startLanguageServer(ctx, installResult.resourcePaths, registryUrl)
+            )
         })
     } catch (err) {
         const e = err as ToolkitError
         getLogger('amazonqLsp').warn(`Failed to start downloaded LSP, falling back to bundled LSP: ${e.message}`)
         try {
             await lspSetupStage('all', async () => {
-                await lspSetupStage('launch', async () => await startLanguageServer(ctx, getBundledResourcePaths(ctx)))
+                await lspSetupStage(
+                    'launch',
+                    async () => await startLanguageServer(ctx, getBundledResourcePaths(ctx), registryUrl)
+                )
             })
         } catch (error) {
             void messages.showViewLogsMessage(

packages/amazonq/src/lsp/client.ts

@@ -83,7 +83,8 @@ export function hasGlibcPatch(): boolean {
 
 export async function startLanguageServer(
     extensionContext: vscode.ExtensionContext,
-    resourcePaths: AmazonQResourcePaths
+    resourcePaths: AmazonQResourcePaths,
+    registryUrl?: string
 ) {
     const toDispose = extensionContext.subscriptions
 
@@ -188,6 +189,7 @@ export async function startLanguageServer(
                         codeReviewInChat: codeReviewInChat,
                         // feature flag for displaying findings found not through CodeReview in the Code Issues Panel
                         displayFindings: true,
+                        registryUrl: registryUrl,
                     },
                     window: {
                         notifications: true,

packages/amazonq/src/lsp/config.ts

@@ -12,6 +12,7 @@ import {
 
 export interface ExtendedAmazonQLSPConfig extends BaseLspInstaller.LspConfig {
     ui?: string
+    registryUrl?: string
 }
 
 // Taken from language server runtimes since they are not exported:
@@ -44,10 +45,12 @@ export const defaultAmazonQLspConfig: ExtendedAmazonQLSPConfig = {
 }
 
 export function getAmazonQLspConfig(): ExtendedAmazonQLSPConfig {
+    const registryConfig = DevSettings.instance.get('amazonqRegistry', {})
     return {
         ...defaultAmazonQLspConfig,
         ...(DevSettings.instance.getServiceConfig('amazonqLsp', {}) as ExtendedAmazonQLSPConfig),
         ...getServiceEnvVarConfig('amazonqLsp', Object.keys(defaultAmazonQLspConfig)),
+        registryUrl: (registryConfig as any)?.registryUrl,
     }
 }
 /**

packages/amazonq/test/unit/amazonq/lsp/config.test.ts

@@ -11,6 +11,7 @@ import { defaultAmazonQLspConfig, ExtendedAmazonQLSPConfig, getAmazonQLspConfig
 describe('getAmazonQLspConfig', () => {
     let sandbox: sinon.SinonSandbox
     let serviceConfigStub: sinon.SinonStub
+    let getStub: sinon.SinonStub
     const settingConfig: ExtendedAmazonQLSPConfig = {
         manifestUrl: 'https://custom.url/manifest.json',
         supportedVersions: '4.0.0',
@@ -24,8 +25,10 @@ describe('getAmazonQLspConfig', () => {
         sandbox = sinon.createSandbox()
 
         serviceConfigStub = sandbox.stub()
+        getStub = sandbox.stub()
         sandbox.stub(DevSettings, 'instance').get(() => ({
             getServiceConfig: serviceConfigStub,
+            get: getStub,
         }))
     })
 
@@ -36,29 +39,45 @@ describe('getAmazonQLspConfig', () => {
 
     it('uses default config', () => {
         serviceConfigStub.returns({})
-        assert.deepStrictEqual(getAmazonQLspConfig(), defaultAmazonQLspConfig)
+        getStub.returns({})
+        assert.deepStrictEqual(getAmazonQLspConfig(), { ...defaultAmazonQLspConfig, registryUrl: undefined })
     })
 
     it('overrides path', () => {
         const path = '/custom/path/to/lsp'
         serviceConfigStub.returns({ path })
+        getStub.returns({})
 
         assert.deepStrictEqual(getAmazonQLspConfig(), {
             ...defaultAmazonQLspConfig,
             path,
+            registryUrl: undefined,
         })
     })
 
     it('overrides default settings', () => {
         serviceConfigStub.returns(settingConfig)
+        getStub.returns({})
 
-        assert.deepStrictEqual(getAmazonQLspConfig(), settingConfig)
+        assert.deepStrictEqual(getAmazonQLspConfig(), { ...settingConfig, registryUrl: undefined })
     })
 
     it('environment variable takes precedence over settings', () => {
         setEnv(settingConfig)
         serviceConfigStub.returns({})
-        assert.deepStrictEqual(getAmazonQLspConfig(), settingConfig)
+        getStub.returns({})
+        assert.deepStrictEqual(getAmazonQLspConfig(), { ...settingConfig, registryUrl: undefined })
+    })
+
+    it('includes registryUrl from amazonqRegistry setting', () => {
+        const registryUrl = 'https://custom.registry.url/manifest.json'
+        serviceConfigStub.returns({})
+        getStub.withArgs('amazonqRegistry', {}).returns({ registryUrl })
+
+        assert.deepStrictEqual(getAmazonQLspConfig(), {
+            ...defaultAmazonQLspConfig,
+            registryUrl,
+        })
     })
 
     function setEnv(envConfig: ExtendedAmazonQLSPConfig) {

packages/core/src/shared/settings.ts

@@ -778,6 +778,7 @@ const devSettings = {
     codewhispererService: Record(String, String),
     amazonqLsp: Record(String, String),
     amazonqWorkspaceLsp: Record(String, String),
+    amazonqRegistry: Record(String, String),
     cloudformationLsp: Record(String, String),
     ssoCacheDirectory: String,
     autofillStartUrl: String,