Limits and Constants

Limits and ConstantsEvery bound the system enforces, with its constant name and literal value.

Every number the runtime enforces, in one place. Names are the actual constants; look them up rather than hard-coding the values.

Model-facing bounds

Constant	Value	What it bounds
`MAX_MODEL_TOOL_RESULT_BYTES`	8 KiB	The text of a single tool result as the model sees it (~2k tokens). Applied live and again on replay
`MAX_TOOL_RESULT_BYTES`	256 KiB	The stored/structural tool result cap; over it, output is truncated with a marker
`SPACE_INDEX_BUDGET_BYTES`	2 KiB	The `<space>` index in every system prompt (Tools)
`MAX_PROMPT_BYTES`	64 KiB	An agent's system prompt
`MAX_MESSAGE_TEXT_BYTES`	64 KiB	One user message
`MAX_CONTEXT_LINES` / `MAX_CONTEXT_LINE_BYTES`	64 / 2 KiB	Client window context

Delegation and continuation

Constant	Value	What it bounds
`MAX_SESSION_SPAWN_DEPTH`	3	How deep delegation may nest
`MAX_SESSION_SPAWNS_PER_SESSION`	10	Children one session may spawn
`MAX_RETURN_RESULT_RETRIES`	3	Typed-result validation retries before the child gives up
`MAX_RUN_CONTINUATIONS`	3	Obligation asks before an honest ending
`AGENT_RUN_MAX_ATTEMPTS`	3	Attempts for a background run (an interactive turn gets 1 — retrying would hold the session lock)

The run queue

Constant	Value	What it bounds
`LEASE_MS`	60 s	How long a claimed run lease lasts
`RETRY_BASE_MS`	5 s	Exponential backoff base
`RETRY_CAP_MS`	5 min	Backoff ceiling
`maxConcurrentModelRuns`	8	Concurrent agent runs
`maxConcurrentWorkflows`	32	Concurrent script runs
`pollIntervalMs`	1 s	Dispatch fallback poll

Backoff is min(RETRY_BASE_MS × 2^(attempt−1), RETRY_CAP_MS) plus jitter. Retryability is classified, not assumed: a 5xx from a provider is retryable, a 4xx is a config error and is not.

Scripts and execution

Constant	Value	What it bounds
`WORKFLOW_SOURCE_MAX_BYTES`	256 KiB	Script source
`DEFAULT_FUEL_MS`	2 s	Compute between awaits before `fuel-exhausted`
`DEFAULT_MEMORY_BYTES`	64 MiB	QuickJS heap
`DEFAULT_TIMER_PARK_THRESHOLD_MS`	60 s	Sleeps at or above this park; shorter ones hold the VM
`WORKFLOW_JOURNAL_MAX_ENTRIES`	5,000	Journal entries per run
`WORKFLOW_JOURNAL_MAX_BYTES`	8 MiB	Journal bytes per run
`MAX_EXEC_TIMEOUT_SECS`	300	Ceiling on a requested execute timeout (default 60)
`MAX_EXEC_OUTPUT_BYTES`	64 KiB	stdout and stderr, each
`TRIGGER_CHAIN_MAX_HOPS`	8	Trigger chain depth before it is called a loop

Sandboxes default to 1 vCPU and 512 MiB, and the sandbox's own lifetime is the requested timeout plus 30 seconds of grace.

Content and storage

Constant	Value	What it bounds
`MAX_WRITE_CONTENT_BYTES`	256 KiB	Content in one `write`
`MAX_LINK_RESOLUTION_CHECKS`	50	`hm://` links resolved per write (4 at a time)
`MAX_MEMORY_PATH_BYTES` / `MAX_MEMORY_PATH_DEPTH`	512 B / 16	Memory paths — note there is no size quota on memory itself
`MEMORY_DOWNLOAD_IDLE_TIMEOUT_MS`	60 s	Idle (not total) timeout on a download
`MAX_SESSION_ATTACHMENT_BYTES`	100 MiB	One attachment
`MAX_SESSION_ATTACHMENTS`	200	Attachments per session
`MAX_MESSAGE_ATTACHMENTS`	16	Attachments referenced by one message
`MAX_INLINE_IMAGE_BYTES`	~4.5 MB	Image shown inline to a vision model
`MAX_UPLOAD_CHUNK_BYTES` / `MAX_UPLOAD_TOTAL_BYTES`	8 MiB / 2 GiB	Chunked upload
`UPLOAD_TTL_MS` / `MAX_ACTIVE_UPLOADS_PER_ACCOUNT`	1 hour / 8	Upload sessions

Definitions and secrets

Constant	Value
`MAX_NAME_BYTES`	256
`MAX_MODEL_BYTES`	256
`MAX_TOOL_COUNT`	32
`MAX_TOOL_NAME_BYTES`	128
`MAX_TOOLS_TOTAL_BYTES`	4 KiB
`MAX_METADATA_CBOR_BYTES`	16 KiB
`MAX_SECRET_BYTES`	64 KiB
`SECRET_NONCE_BYTES`	12
Tool document source / description	256 KiB / 16 KiB
Tool name pattern	`^[a-z][a-z0-9_-]{1,63}$`

Protocol and paging

Constant	Value
`MAX_ACTION_CLOCK_SKEW_MS`	30 s (also the replay window — see Security)
`HM_READ_TIMEOUT_MS`	30 s
`DEFAULT_SESSION_PAGE_SIZE` / `MAX_SESSION_PAGE_SIZE`	50 / 200
HTTP request body	unbounded, deliberately

Persistence · Operations · Security

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