Azure Functions extension agent guide

TypeScript VS Code extension creates, configures, debugs, deploys, manages local and Azure Function Apps. Use this map to find narrowest owner before editing; matching .github/instructions/*.instructions.md files hold deeper subsystem rules.

Architecture

• src/extension.ts: activation, shared package initialization, command/provider registration, public API, test API.
• src/extensionVariables.ts: process-wide state initialized during activation. Prefer action/wizard context over new globals.
• package.json, package.nls.json: command/view/menu/settings contributions, localized contribution text.
• src/commands/registerCommands.ts: most azureFunctions.* dispatch.
• src/commands/**: command orchestration; multi-step flows use AzureWizard.
• src/tree/**, src/FunctionAppResolver.ts, src/LocalResourceProvider.ts: Azure Resources and workspace tree integration.
• src/workspace/**, src/funcConfig/**, src/vsCodeConfig/**: discovery, Functions/VS Code configuration.
• src/funcCoreTools/**, src/templates/**, src/debug/**: Core Tools, templates, local host, debugger behavior.
• src/utils/azureClients.ts: extension-specific Azure SDK factories.
• src/vscode-azurefunctions.api.d.ts: public contract. src/testApi.ts: test-only contract.
• test/**: VS Code extension tests; live/long-running tests use existing environment gates.

Trace behavior end-to-end before editing:

package.json contribution or API call -> registration -> command/wizard -> shared service/tree model -> refresh/output -> tests.

Azure authentication ownership

Interactive Azure authentication follows this chain:

Functions -> Azure Resources extension -> @microsoft/vscode-azext-azureauth -> vscode.authentication -> built-in Microsoft Authentication provider.

• src/extension.ts acquires the legacy Azure Resources host API (ext.rgApi) and current API (ext.rgApiV2). Azure Resources owns Azure account/subscription selection and supplies authenticated subscription objects; Functions does not implement a separate Azure sign-in provider.
• src/FunctionAppResolver.ts receives ISubscriptionContext from Azure Resources. src/tree/SubscriptionTreeItem.ts passes the selected subscription to Azure client factories. src/utils/azureClients.ts delegates to shared createAzureClient/createAzureSubscriptionClient, which use the supplied credentials and cloud endpoint.
• The shared auth package implements account/subscription discovery and session-backed credentials. Its getSessionFromVSCode helper calls vscode.authentication.getSession with the configured provider, resource scopes and tenant. Public Azure uses provider ID microsoft; sovereign/custom clouds use microsoft-sovereign-cloud.
• Durable Task Scheduler uses the current API's AzureSubscription.authentication: src/tree/durableTaskScheduler/DurableTaskSchedulerClient.ts requests a session through that object rather than creating another credential chain.
• For sign-in/session failures, trace Azure Resources and the auth package before changing Functions command code. Inspect VS Code's Microsoft Authentication logs (Developer: Show Logs...); check the selected account, tenant, cloud and requested audience without recording tokens or account identifiers. Successful az login does not establish a VS Code Microsoft Authentication session. Explicit CI/federated test providers are separate from this interactive flow.

Command wiring

• Change command title, visibility, menu, keybinding, setting, activation, or when clause in package.json, package.nls.json.
• Change command arguments/dispatch in src/commands/registerCommands.ts.
• Function Host debug-view commands registered in src/debug/registerFunctionHostDebugView.ts.
• Debug providers, task provider, resolvers, workspace providers, URI handling, APIs registered in src/extension.ts.
• src/agent/agentIntegration.ts advertises agent-invokable commands, adapts queued wizard input.
• src/commands/api/**: thin public API adapters; product behavior stays in normal command/service implementations.

Direct command ownership

• App lifecycle: src/commands/startFunctionApp.ts, stopFunctionApp.ts, restartFunctionApp.ts.
• Function state/deletion: updateDisabledState.ts, deleteFunction.ts, deleteFunctionApp.ts, deleteNode.ts.
• Slots/children: createSlot.ts, swapSlot.ts, createChildNode.ts.
• Navigation/inspection: browseWebsite.ts, openInPortal.ts, viewProperties.ts, openFile.ts.
• URLs/keys: copyFunctionUrl.ts, getMcpHostKey.ts.
• Deployment source/history: configureDeploymentSource.ts, src/commands/deployments/**.
• Core Tools install/update/uninstall: src/funcCoreTools/**.

Convert direct commands to wizard steps when prompts or durable side effects multiply.

Tests

• test/createFunction/**: templates across languages, runtimes, models, sources.
• test/project/**: project scaffolding, VS Code initialization.
• test/nightly/**: gated live-Azure operations.
• Top-level test/*.test.ts: focused utilities, Core Tools, debugging, settings, parsing, compatibility.
• test/api.test.ts, test/utils/testApiAccess.ts, src/testApi.ts: bundled extension boundary.
• test/global.test.ts, test/addParallelSuite.ts, test/utils/**: shared setup, gates, workspaces, contexts, parallel execution.

Place regression coverage beside nearest suite; do not create second harness for behavior already exposed through test API.