# Limits reference (/reference/limits) This page collects the limits and defaults that OpenInspect enforces. Values marked as settings can be changed by an administrator; the rest are fixed. ## Sessions [#sessions] | Limit | Value | Where it applies | | ------------------------------------ | ----------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------- | | Repositories per session target | 10 | Ad-hoc multi-repository sets and environments | | Prompt length | 64,000 characters | Web prompts and child follow-up prompts sent with `send-child-prompt` | | Unfinished prompts per session | 50 | Prompts that are pending or processing. A further prompt is rejected with "A session may have at most 50 unfinished prompts" | | Images per prompt | 6 | Web and Slack prompts | | Image size | 10 MiB each | PNG, JPEG, WebP, or GIF | | Concurrent child sessions per parent | 5 by default | Sandbox setting `maxConcurrentChildSessions` | | Total child sessions per parent | 15 by default | Sandbox setting `maxTotalChildSessions` | | Session cost limit | Blank by default (no limit); a positive USD amount when set | Sandbox setting `maxSessionCostUsd`, overridable per session from the Budget sidebar section | ## Boot and sandbox [#boot-and-sandbox] | Limit | Value | Where it applies | | --------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- | | Connect watchdog | 4 minutes | From sandbox creation until the runtime first connects. Covers the provider launching the container, not your scripts | | Boot budget | 30 minutes by default | From sandbox creation until ready, including `setup.sh` and `start.sh`. Operators change it with `SANDBOX_BOOT_TIMEOUT_MS` | | Heartbeat timeout | 90 seconds | While connected (booting or ready), a runtime that stops sending heartbeats for this long is marked `stale` and stopped | | Heartbeat interval | 30 seconds | How often the runtime reports in while connected | | Tunnel ports | 10 | Sandbox setting `tunnelPorts` | | Tunnel URL wait before `start.sh` | 30 seconds by default | `TUNNEL_WAIT_TIMEOUT_SECONDS` in the sandbox; `start.sh` runs without fresh URLs if it expires | | Final snapshot buffer | 10 minutes by default, 5 minutes minimum | Sandbox setting `finalSnapshotBufferMs`: time reserved before provider expiry to save state | | Sandbox lifetime | Blank: 2 hours on Modal and E2B, 45 minutes (the maximum) on Vercel, the provider's own default on OpenComputer. When set: whole seconds, at least 1 second | Sandbox setting `sandboxTimeoutMs` | | Prompt execution timeout | The configured sandbox timeout; otherwise the operator's `EXECUTION_TIMEOUT_MS`; otherwise 2 hours | How long a message may stay processing before it is failed | ## Secrets [#secrets] | Limit | Value | Where it applies | | -------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ | | Secrets per scope | 50 | Global, repository, and environment scopes | | Key length | 256 characters | Any scope | | Key format | Letters, digits, and underscores; cannot start with a digit | Any scope | | Value size | 16 KB | One secret | | Total value size per scope | 64 KB | One scope | | Combined size per session | 128 KB | Global plus the session target's secrets after merging. A larger payload fails the spawn with a per-scope byte breakdown | | Reserved keys | `PYTHONUNBUFFERED`, `SANDBOX_ID`, `CONTROL_PLANE_URL`, `SANDBOX_AUTH_TOKEN`, `REPO_OWNER`, `REPO_NAME`, `GITHUB_APP_TOKEN`, `SESSION_CONFIG`, `RESTORED_FROM_SNAPSHOT`, `OPENCODE_CONFIG_CONTENT`, `PATH`, `HOME`, `USER`, `SHELL`, `TERM`, `PWD`, `LANG` | Cannot be saved as secrets; the form shows a validation error | ## Managed skills [#managed-skills] | Limit | Value | Where it applies | | ---------------------------------- | -------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------- | | Canonical name | 64 characters | Must be unique. `agent-browser`, `record-video`, `upload-screenshot`, `visual-verification`, and `customize-opencode` are reserved | | Description | 1,024 characters | Skill metadata | | License | 200 characters | Skill metadata | | Compatibility | 500 characters | Skill metadata | | Metadata key / value | 100 / 500 characters | Skill metadata | | Supporting files | 99 per skill revision | Files beside the generated `SKILL.md` | | Individual file | 256 KiB | One supporting file | | Complete skill revision | 1 MiB | Instructions plus supporting files | | Managed skill content in a session | 5 MiB | All installed skills together | | Supporting-file path | Relative, `/` separators, no `.` or `..` segments, at most 10 segments or 240 UTF-8 bytes, no control characters, not `SKILL.md` | Each supporting file | ## Automations [#automations] | Limit | Value | Where it applies | | -------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Name length | 200 characters | Any automation | | Instructions length | 15,000 characters | Any automation | | Repositories and environments per automation | 10 combined | Multi-select is available on schedule triggers only | | Minimum schedule interval | 15 minutes | Cron schedules | | Webhook payload size | 64 KB | Inbound webhook triggers | | Concurrent runs | 1 per automation | Scheduled and manual firings; a firing during an active run is recorded as Skipped | | Consecutive failures before auto-pause | 3 | Timed-out runs count as failures; partial failures never reset the counter | | Run execution timeout | The session's execution budget (the configured sandbox timeout for the run's scope, otherwise the operator's `EXECUTION_TIMEOUT_MS`, otherwise 2 hours), plus a 100-minute sweep grace | The session fails its own prompt at the budget. If that result never reaches the scheduler, a sweep fails the run with `execution_timeout` once the grace has also passed. Timed-out runs count toward auto-pause | | Slack thread continuation | 7 days | Replies in a triggering thread continue the same session | | Slack thread context | 20 earlier messages, 1,024 characters each | Passed to the agent when the triggering message is a reply | | Automations list page | 25 by default, 100 at most | `GET /automations` | | Invocation history page | 100 at most | `GET /automations/:id/invocations` | ## Prebuilt images [#prebuilt-images] | Limit | Value | Where it applies | | -------------------- | ----------------------------------------- | ----------------------------------------------------------------------------------------------------- | | Build timeout | 30 minutes by default, 60 minutes at most | Sandbox setting `buildTimeoutSeconds`; covers clone and `setup.sh` | | Vercel build cap | 35 minutes | Vercel limits sandbox lifetime to 45 minutes, so execution is capped to keep the finalization reserve | | Finalization reserve | 10 minutes on top of the build timeout | Callback delivery and snapshot or checkpoint capture | | Rebuild scheduler | Every 30 minutes | Checks each enabled scope for new commits, a missing image, or an outdated runtime | | Builds per scope | 1 at a time | A trigger while a build is in flight is a no-op | ## Slack [#slack] | Limit | Value | Where it applies | | ---------------------------------------------- | ---------------------------------------- | ---------------------------------------------------------------------------------------------------------- | | Images per message | 6, 10 MiB each | Attached images and images inside forwarded messages, PNG, JPEG, WebP, or GIF | | Forwarded messages per request | 10 | Each shared message's text is truncated at 4,000 characters | | Generated media per completion | 5 files, 10 MiB per file, 25 MiB total | Media delivery, when the operator enables it | | Target dropdown lifetime | 1 hour | The original request is kept while you pick a repository or environment | | Thread-to-session mapping | About 7 days | Replies after that may start target selection again | | Thread messages included with a follow-up | Up to 10 | Messages posted after the previous prompt and before the new request | | Thread context for channel-message automations | Up to 20 messages, 1,024 characters each | Only when the triggering message is a reply | | Session instructions | 10,000 characters | Settings › Integrations › Slack › Session Instructions, appended to the first prompt of new Slack sessions | | Routing rules | 100 rules, 100-character keywords | Settings › Integrations › Slack › Routing rules | ## Linear [#linear] | Limit | Value | Where it applies | | ------------------------ | ------ | ------------------------------------------------------------- | | Issue-to-session mapping | 7 days | After it expires, a new agent request may start a new session | ## PR Feedback Autofix [#pr-feedback-autofix] | Limit | Value | Where it applies | | --------------------------------- | -------------------------- | -------------------------------------------------------------------------------------------------- | | Attempts per pull request | 30 per 24 hours by default | Settings › Integrations › GitHub › PR Feedback Autofix; "No Autofix attempt limit" removes the cap | | Review comments per feedback item | 100 | One submitted review | | Diff hunk per review comment | 4,000 characters | Longer hunks are truncated and flagged | | Prompt size | 200,000 bytes | The follow-up prompt built from the feedback | ## Analytics [#analytics] | Limit | Value | Where it applies | | ---------- | ---------------------------------------- | ------------------ | | Time range | 7, 14, 30, or 90 days; 30 is the default | The Analytics page | ## Next steps [#next-steps] * [Sandbox settings](/configure/sandbox-settings) * [Secrets](/configure/secrets) * [Status reference](/reference/statuses)