Limits reference

Every bound BrowserMesh enforces, in one table. Defaults are what an unconfigured server uses; the range is what the environment variable accepts.

Exceeding a bound produces LIMIT_EXCEEDED when the request cannot be served, or a truncated result flagged in the response when it can. The two are different outcomes and both are explicit — no result is silently shortened.

Runtime

Bound	Default	Range	Set with
Operation timeout	10,000ms	1–300,000	BROWSERMESH_TIMEOUT_MS
Live sessions	50	1–1,000	BROWSERMESH_MAX_SESSIONS
Pages per session	20	1–100	BROWSERMESH_MAX_PAGES

timeoutMs on an individual call overrides the default for that call, up to 300,000ms.

Snapshots

browser_snapshot bounds are fixed in the build, not configurable. Per-call arguments may lower them but never raise them past the maximum.

Bound	Default	Per-call maximum	Argument
Returned characters	50,000	100,000	maxChars
Returned bytes	65,536	131,072	maxBytes
Tree depth	unbounded	100	maxDepth
Element refs	50	100	maxRefs
Children per node	unbounded	1,000	maxChildren
Source DOM nodes	20,000	—	—
Source characters	2,000,000	—	—
Retained captures / page	4	—	—
Cursor lifetime	30s	—	—
Element ref lifetime	30s	—	—

maxChars and maxBytes both apply; whichever binds first truncates, and truncation.byMaxChars / truncation.byMaxBytes say which did. For ASCII text characters bind first. For content averaging three bytes per character the byte bound is reached at roughly 21,800 characters, so the same arguments return less text on a CJK page than on an English one — by design, and reported.

A source page over 20,000 DOM nodes or 2,000,000 characters is rejected with LIMIT_EXCEEDED before serialization rather than truncated. Scope the snapshot to a container with scope.

Cursors and refs both expire 30 seconds after capture and are invalidated by navigation or page close, whichever comes first.

Reading page text

Bound	Default	Range	Set with
Characters	20,000	128–1,000,000	BROWSERMESH_VISIBLE_TEXT_MAX_CHARS
Bytes	65,536	512–4,194,304	BROWSERMESH_VISIBLE_TEXT_MAX_BYTES

browser_visible_text has no per-call bound argument and no cursor. When truncation.truncated is true, the remedy is a narrower locator or a server-side change to the limit — not a follow-up call. Use browser_snapshot, which paginates, when the whole of a long page is needed.

Observability

Bound	Default	Range	Set with
Retained events per page	200	1–1,000	BROWSERMESH_OBSERVABILITY_EVENTS
Events per response	100	1–200	BROWSERMESH_OBSERVABILITY_PAGE_SIZE
Captured string length	2,048	128–8,192	BROWSERMESH_OBSERVABILITY_STRING_CHARS
Response bytes	65,536	1,024–262,144	BROWSERMESH_OBSERVABILITY_RESPONSE_BYTES

browser_observe's limit argument is validated against the configured events per response, not against the maximum the published schema allows. On a default server limit: 150 is accepted by the schema and rejected by the runtime with INVALID_ARGUMENT; the safe ceiling is 100 unless the operator raised it.

The event buffer is a ring. When it overflows, droppedCount and gap say so. Read both before concluding that something did not happen.

Screenshots

Bound	Default	Range	Set with
Dimension (pixels)	10,000	256–32,768	BROWSERMESH_SCREENSHOT_MAX_DIMENSION
Total pixels	40,000,000	65,536–268,435,456	BROWSERMESH_SCREENSHOT_MAX_PIXELS
Encoded bytes	16 MiB	1,024–64 MiB	BROWSERMESH_SCREENSHOT_MAX_BYTES

A full-page capture of a long page reaches the pixel or byte bound before the dimension bound. Capture a single element instead of raising the limit.

Session labels

Fixed in the build. Names and metadata are workflow labels, not identity.

Bound	Value
Name characters / bytes	128 / 512
Metadata entries	32
Metadata key chars/bytes	64 / 256
Metadata value chars/bytes	512 / 2,048
Metadata aggregate bytes	8,192

Control characters are rejected, as are the keys __proto__, constructor, and prototype.

Saved state

Bound	Default	Range	Set with
Saved states	100	1–10,000	BROWSERMESH_MAX_SAVED_STATES
Bytes per state	1 MiB	1,024–64 MiB	BROWSERMESH_MAX_STATE_BYTES
Bytes in total	16 MiB	1,024–1 GiB	BROWSERMESH_MAX_STATE_TOTAL_BYTES

stateId is 1–128 characters from a safe identifier set.

Argument bounds

Enforced by the published input schemas.

Argument	Bound
timeoutMs	1–300,000
url matcher value	2,048 characters
URL glob wildcards	32
wait text	2,000 characters
Dialog promptText	2,000 characters
key	1–64 characters
Iframe chain depth	1–5 selectors
stateId, sinceEventId	1–128 characters
Snapshot cursor	1–160 characters

What browser_runtime_info reports

browser_runtime_info returns the session, screenshot, visible-text, and persistence limits plus the timeout, session, and page counts. It does not report snapshot bounds, observability bounds, or the 30-second cursor and ref lifetimes. Those are fixed in the build or come from environment variables the tool does not echo; this page is the reference for them.