Stack specs

A stack is a sleeve's specification: a YAML document saved in versions on the Specs page. Saving makes a new version; applying a version to a Dock moves the sleeve onto it. Older versions stay readable, so you can always go back.

The form or the YAML

When you press NEW STACK or EDIT, the editor opens on the FORM tab: plain fields for everything most sleeves need. The YAML tab shows the same spec as text. Both edit one spec, so you can switch at any moment, and what you save is always the YAML.

The form keeps every setting it does not show (other capabilities, shared memory, runtime and so on), so experts can still add those in the YAML. Two things to know:

• A change made in the form rewrites the YAML in a standard order and drops # comments. The editor tells you when the spec has comments.
• If the YAML cannot be read (for example while you are halfway through typing in it), the form waits: fix the YAML, then switch back.

SHOW CHANGES compares the draft with the version you started from, whichever tab you used.

A complete example

apiVersion: sleeve/v1
kind: Stack
metadata:
  name: scout
  tenant: acme
conscience:
  provider: anthropic
  model: claude-haiku-5-5
  apiKeySecretRef: anthropic-main
  params: { maxTokens: 1024, temperature: 0.3 }
role:
  title: "Scout"
  systemPrompt: |
    You watch for news about our market and answer in one short paragraph.
    Remember what you learn with your memory tools.
capabilities:
  - mcp:memory:private
memory:
  backend: nats-kv
  private: acme/scout
comms:
  triggers:
    - { type: nats-subject, subject: acme.events.scout }
guards: { maxIterations: 6, tokenBudget: 40000, wallClockSeconds: 240 }

Fields

Capabilities

Shells, host folders and integrations such as Slack are not available to sleeves on Docks. Tools from other services come as MCP servers.

Triggers

Every sleeve also answers Converse messages and API calls, whatever its triggers.

Routines

A routine is a standing job: at its time, the sleeve is handed the routine's task, exactly as if someone had sent it that message.

routines:
  - name: nightly-results
    cron: "0 7 * * 1-5"            # minute hour day month weekday
    tz: America/Costa_Rica          # read the cron in this time zone; empty means UTC
    task: |
      Read last night's test run. List the new failures and their likely causes,
      and open or update a ClickUp ticket for each real failure.
  - name: clickup-triage
    cron: "0 8,13 * * 1-5"
    tz: America/Costa_Rica
    task: Triage the new tickets in the Support list: priority, tags, assignee, and a comment on what is missing.
    enabled: false                  # keep it, but do not run it

• Up to 10 routines; names are lowercase letters, digits and dashes.
• Each run is a task like any other: it counts against the guards and shows on the Events tab with the routine's name.
• Time zones are IANA names such as America/Costa_Rica or Europe/Madrid, daylight saving included. Sleevecast refuses an unknown name and warns about a routine that runs more than 48 times a day.
• In the form, routines are under When it works, with time presets.

Guards

Each task gets at most maxIterations turns of the model, tokenBudget tokens and wallClockSeconds seconds. When one runs out, the sleeve stops the task cleanly, reports which guard tripped, and shows as Guarded on the Fleet until its next task.

• Running out gently. When the token budget would not hold another working turn plus an answer, or the task reaches its last allowed turn, the sleeve stops calling tools and answers with what it has found, saying what it could not finish. A guard trips only when even that cannot fit, for example when a single turn is bigger than the whole budget.
• Cached input is cheap. Every turn re-sends the conversation so far, including the tool definitions of every MCP server and sandbox. With Anthropic models the sleeve marks that unchanged part for the provider's prompt cache, and input read from the cache counts as a tenth of its tokens against tokenBudget, as providers bill it.
• See what a turn carries. When a sleeve starts, its ready event (Events tab) says how many tools it has and roughly how many tokens their definitions add to every turn, per server. A server with dozens of tools can add tens of thousands; list only the tools a sleeve needs with tools on that server.

Rules Sleevecast checks

When you save, the spec is checked against the runtime's schema and these rules, and the console points at the line of each problem:

• metadata.tenant is your alias and metadata.name is the stack's name.
• Only the capabilities above; bus subjects stay inside your organization.
• No secret values in the spec: keys and tokens are named with secretRef, never pasted.
• MCP servers have unique names and either a url or an npx/uvx command; unpinned packages get a warning.
• No image: Sleevecast chooses the signed runtime image.
• No YAML anchors, aliases or custom tags, at most 24 levels deep, at most 32 KB.

The number of stacks your organization can save depends on your plan; new versions of a stack never count.