This release includes 2 breaking changes for platform teams planning a safe upgrade.
✓ No known CVEs patched in this version
Topics
Affected surfaces
ReleasePort's take
Moderate signalstagehand 3.4.0 moves browser drivers to peer dependencies and defaults the agent mode to hybrid with automatic DOM routing for incompatible models.
Why it matters: Install browser drivers (playwright-core, puppeteer-core, or patchright-core) explicitly as peer dependencies. Test hybrid agent mode routing in development before upgrading to production.
Summary
AI summaryDefault agent mode changed to hybrid with automatic DOM routing for incompatible models.
Changes in this release
| Type | Severity | Summary | CVE |
|---|---|---|---|
| Breaking | Medium |
move playwright-core, puppeteer-core, patchright-core from optional dependencies to peer dependencies move playwright-core, puppeteer-core, patchright-core from optional dependencies to peer dependencies Source: llm_adapter@2026-05-21 Confidence: low |
— |
| Feature | Medium |
add ignoreSelectors parameter to extract() add ignoreSelectors parameter to extract() Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Feature | Medium |
add ignoreSelectors option to observe() add ignoreSelectors option to observe() Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Feature | Medium |
Strengthen observe prompts so LLMs return complete encoded element IDs. Strengthen observe prompts so LLMs return complete encoded element IDs. Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Feature | Medium |
Set default agent mode to hybrid with auto routing to dom for non compatible models Set default agent mode to hybrid with auto routing to dom for non compatible models Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Feature | Medium |
Add support for CUA models: openai/gpt-5.4-mini, openai/gpt-5.5, anthropic/claude-haiku-4-5 Add support for CUA models: openai/gpt-5.4-mini, openai/gpt-5.5, anthropic/claude-haiku-4-5 Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Deprecation | Medium |
Prefer `STAGEHAND_API_URL` over deprecated `STAGEHAND_BASE_URL` for API overrides Prefer `STAGEHAND_API_URL` over deprecated `STAGEHAND_BASE_URL` for API overrides Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Deprecation | Low |
Deprecate Browserbase project ID configuration Deprecate Browserbase project ID configuration Source: granite4.1:30b@2026-05-23-audit Confidence: low |
— |
| Bugfix | Medium |
Fix frame registry handling for OOPIF pages Fix frame registry handling for OOPIF pages Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Bugfix | Medium |
Remove the default temperature setting from v3 agent AI SDK calls for non-compatible models Remove the default temperature setting from v3 agent AI SDK calls for non-compatible models Source: llm_adapter@2026-05-21 Confidence: high |
— |
| Bugfix | Medium |
Add variables support to v3 agentExecute API schema and remove experimental requirement Add variables support to v3 agentExecute API schema and remove experimental requirement Source: llm_adapter@2026-05-21 Confidence: low |
— |
| Bugfix | Medium |
bump transitive dependencies to patched versions bump transitive dependencies to patched versions Source: llm_adapter@2026-05-21 Confidence: low |
— |
Full changelog
Minor Changes
-
#2084
0641d44Thanks @seanmcguire12! - add ignoreSelectors param to extract() -
#2096
a11603dThanks @seanmcguire12! - add ignoreSelectors to observe()
Patch Changes
-
#2080
21c78b3Thanks @miguelg719! - Add variables support to v3 agentExecute API schema and remove experimental requirement -
#2077
f437f73Thanks @monadoid! - Fix frame registry handling for OOPIF pages -
#2098
a783b99Thanks @seanmcguire12! - bump transitive deps to patched versions -
#2089
8d2f354Thanks @shrey150! - Strengthen observe prompts so LLMs return complete encoded element IDs. -
#2047
a87c1fcThanks @tkattkat! - Set default agent mode to hybrid with auto routing to dom for non compatible models -
#2101
26e6c96Thanks @seanmcguire12! - move playwright-core, puppeteer-core, patchright-core from optional dependencies to peer dependencies -
#2068
1d176c4Thanks @filip-michalsky! - Remove the default temperature setting from v3 agent AI SDK calls so reasoning models that do not support temperature run without provider warnings. -
#2040
1fa9613Thanks @monadoid! - PreferSTAGEHAND_API_URLfor Stagehand API overrides while retainingSTAGEHAND_BASE_URLas a deprecated fallback. -
#2065
9ff70ddThanks @miguelg719! - Add support for CUA models: openai/gpt-5.4-mini, openai/gpt-5.5, and anthropic/claude-haiku-4-5 -
#2039
7640381Thanks @monadoid! - Deprecate Browserbase project ID configuration.
Breaking Changes
- move playwright-core, puppeteer-core, patchright-core from optional dependencies to peer dependencies
- Deprecate Browserbase project ID configuration
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Related context
Related tools
Earlier breaking changes
- vstagehand-server-v3/v3.7.0 Delete packages/server-v4 entirely.
- vstagehand-server-v3/v3.6.10 Remove cli release workflow
- vstagehand-server-v3/v3.6.9 Integration libraries moved to peer dependencies.
Beta — feedback welcome: [email protected]