Architecture

Extension inventory

Roder's /extensions page is backed by the app-server extensions/list method. It reports the extensions installed in the active runtime registry, not every crate that happens to exist in the repository.

Runtime truth. Configuration decides the final list. API keys, web-search settings, subagent definitions, notification settings, and custom distributions can all add or suppress entries.

Discovery contract

Clients call extensions/list and receive manifests plus capability statuses:

{
  "method": "extensions/list",
  "params": null
}

Each manifest contains:

id, name, version, and api_version.
description for UI display.
provides, the typed services installed into the registry.
required_capabilities, the sensitive access requested by the extension.

Service types

Extensions can contribute these services:

InferenceEngine
ContextProvider
ContextPlanner
SessionStore
CheckpointStore
MemoryStore
EmbeddingProvider
ToolProvider
SubagentDispatcher
PolicyContributor
EventSink
TaskExecutor
NotificationSink
InteractiveRegionHandler
RemoteRunnerProvider
StatusSegment
PaletteSource

Built-in host extensions

Runtime id	Provides	Purpose	Capabilities
`roder-ext-mock-provider`	`InferenceEngine(mock)`	Deterministic local provider for tests and offline development.	none
`roder-ext-codex-oauth-provider`	`InferenceEngine(codex)`	Codex provider backed by ChatGPT OAuth credentials.	none declared
`roder-ext-builtin-echo-tools`	`ToolProvider(builtin-echo)`	Offline `echo` tool provider.	none
`roder-ext-builtin-coding-tools`	`ToolProvider(builtin-coding-tools)`	Workspace file, search, patch, edit, workflow, media, shell, and command tools.	`fs.read.workspace`, `fs.write.workspace`, `process.spawn.shell`
`roder-ext-zerolang`	`ToolProvider(zerolang)`	Zero compiler diagnostics, graph inspection, and checked ProgramGraph edit tools.	`fs.read.workspace`, `fs.write.workspace`, `process.spawn.shell`
`roder-ext-default-tui`	`StatusSegment(...)`, `PaletteSource(...)`	Built-in TUI status line and command-palette surfaces.	none

The default TUI extension installs status segments for mode, model, session, branch, usage, mcp, and runner. It also installs palette sources for commands, sessions, agents, models, modes, workflow-imports, and media.

Inference providers

Runtime id	Provides	When installed	Capabilities
`roder-ext-openai-responses-openai`	`InferenceEngine(openai)`	When OpenAI credentials are configured. Runtime id is `roder-ext-openai-responses-{provider_id}`.	`network.api.openai.com`, `secret.read.OPENAI_API_KEY`
`roder-ext-openai-chat-completions`	`InferenceEngine(openai-chat-completions)`	Implemented, but not installed by the default host path.	`network.api.openai.com`, `secret.read.OPENAI_API_KEY`
`roder-ext-anthropic`	`InferenceEngine(anthropic)`	When Anthropic credentials are configured.	`network.api.anthropic.com`, `secret.read.ANTHROPIC_API_KEY`
`roder-ext-gemini`	`InferenceEngine(gemini)`	When Gemini credentials are configured.	`network.api.googleai`, `secret.read.GEMINI_API_KEY`
`roder-ext-cursor`	`InferenceEngine(cursor)`	Installed by default; live turns require a Cursor User API Key.	`network.agentn.global.api5.cursor.sh`, `network.api2.cursor.sh`
`roder-ext-openrouter-provider`	`InferenceEngine(openrouter)`	Installed by default; live turns require an OpenRouter API key. Includes the built-in `x-ai/grok-build-0.1` Grok Build route.	`network.openrouter.ai`, optionally `secret.read.OPENROUTER_API_KEY`
`roder-ext-xai`	`InferenceEngine(supergrok)`; also `InferenceEngine(xai)` with an API key.	Installed by default. Direct xAI API-key surface is conditional.	`network.api.x.ai`; optionally `secret.read.XAI_API_KEY`
`roder-ext-opencode-provider`	`InferenceEngine(opencode)`, `InferenceEngine(opencode-go)`	Installed by default.	`network.opencode.ai`
`roder-ext-poolside-provider`	`InferenceEngine(poolside)`	Installed by default.	`network.inference.poolside.ai`

Storage, memory, and embeddings

Runtime id	Provides	Purpose	Capabilities
`roder-ext-jsonl-session`	`SessionStore(jsonl)`	Append-only JSONL session persistence under Roder home.	`fs.readwrite.roder-home`
`roder-ext-memory`	`MemoryStore(sqlite-memory)`, `ContextProvider(memory-context)`, `ToolProvider(memory-tools)`	SQLite-backed project/global memory, memory context, and memory tools.	`fs.readwrite.roder-home`
`roder-ext-openai-embeddings`	`EmbeddingProvider(openai)`	OpenAI embedding provider for memories.	`network.openai`, `secrets.openai-api-key`

Policy, tasks, subagents, and notifications

Runtime id	Provides	When installed	Capabilities
`roder-ext-plan-mode`	`PolicyContributor(plan-mode)`	Installed by default.	none
`roder-ext-task-process`	`TaskExecutor(process)`	Installed by default.	`process.spawn.shell`
`roder-ext-task-subagent`	Currently none declared in the manifest.	Implemented, but not installed by the default host path.	`process.spawn.roder`
`roder-ext-subagents`	`SubagentDispatcher(in-process-subagents)` and a task tool provider.	Only when subagents are enabled and valid agent definitions are loaded.	`process.spawn.roder`
`roder-ext-notify-terminal`	`NotificationSink(terminal-bell)`	When notifications and terminal notifications are enabled.	`terminal.write`
`roder-ext-notify-desktop`	`NotificationSink(desktop)`	When notifications and desktop notifications are enabled.	`desktop.notification`

The default notification kinds are NeedsInput, TurnIdle, TaskCompleted, and TaskFailed.

Web search

Web search has a canonical router plus optional provider-specific tools. The router exposes the unified local web_search tool when external web-search mode is configured.

Runtime id	Provides	Purpose	Capabilities
`roder-ext-web-search`	`ToolProvider(web-search)`	Canonical `web_search` router backed by Firecrawl, Perplexity, Tavily, or Parallel.	`network.web`
`roder-ext-firecrawl-search`	`ToolProvider(firecrawl-search)`	Firecrawl-backed search and retrieval tools.	`network.api.firecrawl.dev`, `secret.read.FIRECRAWL_API_KEY`
`roder-ext-perplexity-search`	`ToolProvider(perplexity-search)`	Perplexity raw Search API tools.	`network.api.perplexity.ai`, `secret.read.PERPLEXITY_API_KEY`
`roder-ext-tavily-search`	`ToolProvider(tavily-search)`	Tavily-backed web search tools.	`network.api.tavily.com`, `secret.read.TAVILY_API_KEY`
`roder-ext-parallel-search`	`ToolProvider(parallel-search)`	Parallel.ai objective-oriented search tools.	`network.web`

Remote runners

Remote runner extensions install providers behind a common protocol for files, commands, ports, snapshots, mounts, artifacts, and provider state.

Runtime id	Provides	Purpose	Capabilities
`roder-ext-runner-unix-local`	`RemoteRunnerProvider(unix-local)`	Local Unix workspace runner.	`fs.readwrite.workspace`, `process.spawn.shell`
`roder-ext-runner-docker`	`RemoteRunnerProvider(docker)`	Local Docker container runner.	`fs.readwrite.workspace`, `process.spawn.docker`
`roder-ext-runner-blaxel`	`RemoteRunnerProvider(blaxel)`	Hosted Blaxel runner.	`network.http`, `secret.read.BLAXEL_API_KEY`
`roder-ext-runner-cloudflare`	`RemoteRunnerProvider(cloudflare)`	Hosted Cloudflare runner.	`network.http`, `secret.read.CLOUDFLARE_API_TOKEN`
`roder-ext-runner-daytona`	`RemoteRunnerProvider(daytona)`	Hosted Daytona runner.	`network.http`, `secret.read.DAYTONA_API_KEY`
`roder-ext-runner-e2b`	`RemoteRunnerProvider(e2b)`	Hosted E2B runner.	`network.http`, `secret.read.E2B_API_KEY`
`roder-ext-runner-modal`	`RemoteRunnerProvider(modal)`	Hosted Modal runner.	`network.http`, `secret.read.MODAL_TOKEN_SECRET`
`roder-ext-runner-runloop`	`RemoteRunnerProvider(runloop)`	Hosted Runloop runner.	`network.http`, `secret.read.RUNLOOP_API_KEY`
`roder-ext-runner-vercel`	`RemoteRunnerProvider(vercel)`	Hosted Vercel runner.	`network.http`, `secret.read.VERCEL_TOKEN`

Catalog and support crates

roder-configure uses distribution catalog ids from crate metadata. Those ids are for profile generation and do not always match runtime manifest ids.

openai-responses can become roder-ext-openai-responses-openai.
xai becomes roder-ext-xai.
jsonl-session becomes roder-ext-jsonl-session.

Two workspace crates are worth calling out: roder-ext-runner-hosted-common is shared hosted-runner support, not a user-facing manifest; roder-ext-disk-context has catalog metadata and helper code, but no runtime RoderExtension implementation was present in the inspected workspace.

Why the list can differ

Missing API keys suppress OpenAI, Anthropic, Gemini, OpenRouter live requests, or direct xAI API-key surfaces.
Notification settings can suppress terminal or desktop notification sinks.
External web search appears only when enabled and configured.
Subagents appear only with valid loaded definitions.
Custom distributions can install a different extension set.