> ## Documentation Index > Fetch the complete documentation index at: https://docs.mcpjam.com/llms.txt > Use this file to discover all available pages before exploring further. # Get or create an unnamed environment for a composed stack > GET-OR-CREATE an UNNAMED, content-addressed environment for a composed stack — a host plus an optional server group, model override, computer image and pinned skills. Distinct from `POST /environments`, which mints a NAMED row that lands in the project's environment list forever. A composed stack is a throwaway: the caller wants to run this exact combination, not to add a permanent entry someone else has to reason about. Deduplicated by a server-side fingerprint of the stack, so the same stack always returns the same environment. `created` says which happened — the status is `200` either way, because get-or-create cannot honestly answer `201` on the dedupe path. A deployment that predates ad-hoc environments answers `400` with `details.reason: "ADHOC_UNAVAILABLE"`. Requires project membership (admin only when the stack pins plugin versions). Promote one to a named environment with `POST /environments/{environmentId}/name`. ## OpenAPI ````yaml /reference/openapi.json post /projects/{projectId}/environments/ensure-adhoc openapi: 3.1.0 info: title: MCPJam API version: 1.0.0-preview description: >- Programmatic access to MCP servers saved in your MCPJam projects — live diagnostics (validate, inspect, export) and operations: call tools, render prompts, run eval suites asynchronously and poll their results, and import OAuth tokens. **The API is in preview**: the surface may change while we finish the design. Error `code` values are stable; error `message` strings are not. Write clients that ignore unknown response fields. contact: name: MCPJam url: https://github.com/MCPJam/inspector/issues servers: - url: https://app.mcpjam.com/api/v1 description: Hosted MCPJam security: - bearerAuth: [] tags: - name: Hosts description: >- Project hosts: named model + capability profiles you run chats and eval suites against. - name: Environments description: >- Project environments: named, live-editable execution bundles (one host, an optional standalone server group, optionally pinned skills and plugin versions) that eval suites and journeys run against. Distinct from Sandbox images, which are Computer base images. Reads require project membership; every write requires project admin. - name: Plugins description: >- Agent Plugins imported into a project — read-only inventory and version detail. - name: Sandbox images description: >- Custom Computer images: a digest-pinned Dockerfile built into an immutable image your project's computers boot from. - name: Server diagnostics description: Connect-level health checks against a saved MCP server. - name: Primitives description: 'The server''s MCP primitives: tools, prompts, and resources.' - name: Export description: Full-server snapshots for diffing and CI. - name: Execution description: 'Run the server''s primitives: call tools, render prompts.' - name: Eval runs description: >- Asynchronous eval suite runs: create with 202, poll status, iterations, and traces. - name: Server connections description: >- Connect an MCP server URL to a project, authorizing in a browser when the server requires it. - name: OAuth description: 'Bring-your-own OAuth: import externally obtained tokens for a server.' - name: Scenarios description: >- Read-only access to the scenarios published from a project: listing, settings, attached servers, and share links. - name: Catalog description: >- Discover the resources the other routes operate on: your account, projects, servers, eval suites, and chat sessions. - name: Tunnels description: >- Relay tunnels that expose local MCP servers through a public URL, registered as first-class project servers (the `mcpjam tunnel` CLI flow). - name: Agent description: >- Headless agent turns over the public API: send a message history, the server runs one assistant turn with project-scoped workspace tools (eval reads + suite creation) on a pinned hosted model, and returns the reply plus created-resource references. - name: Swarms description: >- Personas, journeys and swarm containers — the authoring half of Swarms — plus the model-backed generation that drafts them. - name: Swarm runs description: >- Launching journeys and reading what they produced. Launching SPENDS — see the per-operation notes. - name: Swarm insights description: >- What a swarm run revealed. The scorecard and findings are deterministic and free; requesting wave insights runs models and draws on your shared daily ledger. - name: User testing description: >- Publishing an environment for real visitors, and controlling who can reach it. Several of these NARROW access and take effect immediately. paths: /projects/{projectId}/environments/ensure-adhoc: post: tags: - Environments summary: Get or create an unnamed environment for a composed stack description: >- GET-OR-CREATE an UNNAMED, content-addressed environment for a composed stack — a host plus an optional server group, model override, computer image and pinned skills. Distinct from `POST /environments`, which mints a NAMED row that lands in the project's environment list forever. A composed stack is a throwaway: the caller wants to run this exact combination, not to add a permanent entry someone else has to reason about. Deduplicated by a server-side fingerprint of the stack, so the same stack always returns the same environment. `created` says which happened — the status is `200` either way, because get-or-create cannot honestly answer `201` on the dedupe path. A deployment that predates ad-hoc environments answers `400` with `details.reason: "ADHOC_UNAVAILABLE"`. Requires project membership (admin only when the stack pins plugin versions). Promote one to a named environment with `POST /environments/{environmentId}/name`. operationId: ensureAdhocEnvironment parameters: - $ref: '#/components/parameters/projectId' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AdhocEnvironmentRequest' example: hostId: host_abc123 sandboxImageId: img_def456 responses: '200': description: The environment for this stack, created or reused. content: application/json: schema: $ref: '#/components/schemas/AdhocEnvironmentEnsured' '400': $ref: '#/components/responses/ValidationError' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '500': $ref: '#/components/responses/InternalError' '502': $ref: '#/components/responses/ServerUnreachable' components: parameters: projectId: name: projectId in: path required: true description: ID of the hosted project that contains the server. schema: type: string schemas: AdhocEnvironmentRequest: type: object description: >- A composed stack: the same execution axes a named environment carries, minus the name. required: - hostId additionalProperties: false properties: hostId: type: string description: The host the stack runs as. serverAttachmentId: type: string description: Standalone server group to pin. Omit to use the host's own servers. modelId: type: string description: Model to run instead of the host's pinned one. Stored verbatim. skillSelection: $ref: '#/components/schemas/EnvironmentSkillSelection' pluginVersionIds: type: array minItems: 1 items: type: string description: >- Pinning plugin versions requires project ADMIN; the rest of a stack needs only membership. sandboxImageId: type: string description: >- Project-shared sandbox image to pin, so runs boot a fresh computer from it. AdhocEnvironmentEnsured: type: object required: - environment - created properties: environment: $ref: '#/components/schemas/AdhocEnvironment' created: type: boolean description: >- `false` when the same stack had already been composed. The only way to tell a first compose from a repeat — the status line cannot, because get-or-create answers `200` either way. EnvironmentSkillSelection: type: object description: >- An explicit pinned skill selection. Cannot be empty — clear the field instead (send `null` on update) to mean "no pinned skills". required: - mode - skillIds properties: mode: type: string enum: - explicit skillIds: type: array minItems: 1 items: type: string description: >- Project-shared skill IDs. Skills carrying supporting files or extra frontmatter, and plugin-component skills, cannot be pinned. AdhocEnvironment: type: object description: >- An UNNAMED, content-addressed environment: a composed client/model/computer/skills stack rather than a saved entry in the project's environment list. Its own shape rather than `ProjectEnvironment` with a nullable name, because that schema's `name` is required and every environment listing filters ad-hoc rows out precisely so that promise holds. required: - id - projectId - name - adhoc - hostId - revision - archived - createdAt - updatedAt properties: id: type: string projectId: type: string name: type: - 'null' description: Always `null` — an ad-hoc environment is unnamed by construction. adhoc: type: boolean const: true description: >- Always `true`. Present so a reader never has to infer it from the null name. description: type: string hostId: type: string serverAttachmentId: type: string modelId: type: string description: The stack's model override. Absent means it inherits the host's. skillSelection: $ref: '#/components/schemas/EnvironmentSkillSelection' pluginVersionIds: type: array items: type: string sandboxImageId: type: string revision: type: integer description: Pass back as `expectedRevision` when promoting it with a name. archived: type: boolean archivedAt: type: integer createdAt: type: integer updatedAt: type: integer Error: type: object required: - code - message properties: code: type: string description: >- Stable, machine-readable error code. New codes may be added over time; treat unknown codes as non-retryable failures unless the HTTP status says otherwise. enum: - UNAUTHORIZED - FORBIDDEN - NOT_FOUND - CONFLICT - VALIDATION_ERROR - RATE_LIMITED - FEATURE_NOT_SUPPORTED - SERVER_UNREACHABLE - TIMEOUT - OAUTH_REQUIRED - INTERNAL_ERROR message: type: string description: >- Human-readable description. May change between releases — don't match on it. details: type: object description: Optional, unstructured context bag. additionalProperties: true responses: ValidationError: description: Malformed body or parameters. content: application/json: schema: $ref: '#/components/schemas/Error' example: code: VALIDATION_ERROR message: Invalid JSON body Unauthorized: description: >- Missing, invalid, revoked, or orphaned key (`UNAUTHORIZED`) — or the **target MCP server** needs an OAuth grant (`OAUTH_REQUIRED`), which is a property of the server, not your key. content: application/json: schema: $ref: '#/components/schemas/Error' examples: badKey: summary: Invalid or revoked key value: code: UNAUTHORIZED message: Invalid API key oauthRequired: summary: Target server needs an OAuth grant value: code: OAUTH_REQUIRED message: Server requires OAuth authorization Forbidden: description: Key is valid but not allowed to do this. content: application/json: schema: $ref: '#/components/schemas/Error' example: code: FORBIDDEN message: You do not have access to this project NotFound: description: Unknown project, server, or resource. content: application/json: schema: $ref: '#/components/schemas/Error' example: code: NOT_FOUND message: Server not found InternalError: description: Something failed on MCPJam's side. content: application/json: schema: $ref: '#/components/schemas/Error' example: code: INTERNAL_ERROR message: Unexpected internal error ServerUnreachable: description: Could not connect to the target MCP server. content: application/json: schema: $ref: '#/components/schemas/Error' example: code: SERVER_UNREACHABLE message: Failed to connect to server securitySchemes: bearerAuth: type: http scheme: bearer description: >- MCPJam API key (`sk_…`). Create one at [Settings → API keys](https://app.mcpjam.com/settings/api-keys). Guest sessions cannot use the API, and API keys cannot manage other API keys. ````