…chain-ai#1999)

When a user runs `--sandbox daytona` (or modal/runloop) without the
corresponding extra installed, the CLI spawns a `langgraph dev`
subprocess that crashes with an opaque "Server process exited with code
3." The actual `ImportError` is buried in the subprocess's stderr and
never surfaced. This adds an early dependency check in the CLI process
itself — before the server subprocess is spawned — so users get a clear
error with install instructions.

## Changes
- Add `verify_sandbox_deps()` in `sandbox_factory.py` that uses
`importlib.util.find_spec` to check whether the provider's backend
package (`langchain_daytona`, `langchain_modal`, `langchain_runloop`) is
importable — no actual imports, sub-millisecond cost
- Call `verify_sandbox_deps()` in both the non-interactive and
interactive branches of `cli_main()` before the server subprocess is
launched, printing a clear `Error: Missing dependencies for '<provider>'
sandbox. Install with: pip install 'deepagents-cli[<provider>]'` and
exiting with code 1

> [!CAUTION]
> Merging this PR will automatically publish to **PyPI** and create a
**GitHub release**.

For the full release process, see
[`.github/RELEASING.md`](https://github.com/langchain-ai/deepagents/blob/main/.github/RELEASING.md).

---

_Everything below this line will be the GitHub release body._

---


##
[0.0.35](deepagents-cli==0.0.34...deepagents-cli==0.0.35)
(2026-04-07)

### Highlights

* **Skills:** Invoke SDK skills directly from the CLI with `/skill:name`
or at startup via `--skill`. Skills are a composable extension point for
domain-specific agent behaviors.
* **Themes & configuration:** New theme system with color overrides,
global dotenv at `~/.deepagents/.env`, and a `DEEPAGENTS_CLI_` env var
prefix for conflict-free configuration.
* **Auto-updates:** Full update lifecycle — `/update` to upgrade
in-place, `/auto-update` to toggle background checks, and a refreshed
install script UX.
* **Headless workflows:** Agent-friendly UX for scripted/headless
invocations, AgentCore Code Interpreter sandbox provider, and improved
non-interactive tracing and guidance.
* **Performance:** Sub-250ms first paint via aggressive import deferral
(pydantic, adapters, heavy SDK modules), markdown stack prewarming, and
reduced health-poll intervals.

### Features

* Load `~/.deepagents/.env` as global dotenv
([#1909](#1909))
([5a21d0a](5a21d0a))
* Skill invocation via `/skill:name`
([#2037](#2037))
([cc8cce7](cc8cce7))
* `--skill` startup invocation
([#2477](#2477))
([5f0f1d4](5f0f1d4))
* Auto-update lifecycle, `/update` command, install script ux
([#2095](#2095))
([fd92f6e](fd92f6e))
* `/auto-update` to toggle auto-updates
([#2276](#2276))
([ad70bde](ad70bde))
* Themes
([#2134](#2134))
([db67af0](db67af0))
* Allow color overrides on built-in themes, default dark to false
([#2275](#2275))
([8f71865](8f71865))
* Add `DEEPAGENTS_CLI_` env var prefix and fix dotenv load order
([#2303](#2303))
([29647bb](29647bb))
* Add `ls_integration` metadata to langsmith traces
([#2272](#2272))
([5dd8098](5dd8098))
* Add animated spinner to non-interactive verbose mode
([#2001](#2001))
([153f465](153f465))
* Add async backend support to local context middleware
([#2118](#2118))
([a0d623c](a0d623c))
* Agent-friendly ux for scripted/headless workflows
([#2271](#2271))
([386438f](386438f))
* AgentCore Code Interpreter sandbox provider
([#2120](#2120))
([92556c7](92556c7))
* Context-aware connecting banner for resume and local server
([#2092](#2092))
([18b385b](18b385b))
* Default langsmith project to `'deepagents-cli'`
([#2277](#2277))
([7178b87](7178b87))
* Enhance tool-call UI, add `Ctrl+U` shortcut for chat input
([#1757](#1757))
([800c552](800c552))
* Persist token count in graph state across sessions
([#2323](#2323))
([5be352d](5be352d))
* Pop queued messages individually on `esc` instead of clearing all
([#2089](#2089))
([c76d855](c76d855))
* Render ask-user questions as markdown
([#2339](#2339))
([5fbb14a](5fbb14a))
* Show platform-specific ripgrep install command in missing-tool warning
([#1997](#1997))
([f000ce5](f000ce5))
* Support root/MDM installs
([#2346](#2346))
([f618acc](f618acc))
* Surface unsupported input modalities in system prompt
([#2327](#2327))
([95620e7](95620e7))

### Bug Fixes

* Align headless todo guidance with non-interactive mode
([#2459](#2459))
([281899b](281899b))
* Disable markup parsing for blocked-link notifications
([#2170](#2170))
([15867bf](15867bf))
* Dismiss slash command autocomplete on space
([#2478](#2478))
([02e46bc](02e46bc))
* Eliminate autocomplete popup flicker
([#2020](#2020))
([4b2db1e](4b2db1e))
* Eliminate trace fragmentation in non-interactive mode
([#2136](#2136))
([9bddc52](9bddc52))
* Enforce approval toggle when launched with `-y`
([#2278](#2278))
([28a32b7](28a32b7))
* Escape exception text in rich markup error output
([#2307](#2307))
([42bccca](42bccca))
* Escape markup in toast notifications
([#2139](#2139))
([90ccc28](90ccc28))
* Exit app on `ctrl+d` when thread list is empty
([#2270](#2270))
([e859077](e859077))
* Guard against textual cursor/document desync crash
([#2494](#2494))
([c14a748](c14a748))
* Human-readable duration and consistent dim styling on teardown screen
([#1995](#1995))
([901a0a4](901a0a4))
* Mark token count as approximate after interrupted generation
([#2353](#2353))
([cb9a0c7](cb9a0c7))
* Resolve misleading "missing package" error when provider import fails
([#1960](#1960))
([b90fbad](b90fbad))
* Open trace in browser immediately when busy
([#2305](#2305))
([b452032](b452032))
* Patch model identity in system prompt on `/model` swap
([#2024](#2024))
([36aecbf](36aecbf))
* Harden MCP pre-flight health checks
([#2019](#2019))
([2b27055](2b27055))
* Pre-flight health checks for MCP servers
([#2008](#2008))
([30d60e3](30d60e3))
* Prevent premature thinking state with parallel subtasks
([#1858](#1858))
([189104c](189104c))
* Prevent session stats loss on mid-turn exit
([#2238](#2238))
([b1807aa](b1807aa))
* Rebind toggle tool output to `ctrl+o` to unblock `cmd+right`
([#2088](#2088))
([b486fe5](b486fe5))
* Remove duplicate server failure notification
([#2141](#2141))
([c1cfe72](c1cfe72))
* Remove keybinding overrides that shadow textual built-ins
([#2084](#2084))
([08fc5d0](08fc5d0))
* Resolve conflicting langsmith env var precedence
([#2455](#2455))
([b6997d8](b6997d8))
* Show server startup error instead of generic agent message
([#2397](#2397))
([a3e1e93](a3e1e93))
* Certain slash commands should not require server connection
([#1974](#1974))
([32bd814](32bd814))
* Sort MCP tools deterministically for prompt-cache stability
([#2497](#2497))
([39b43cf](39b43cf))
* Squash loading widget timer leak
([#2396](#2396))
([01d3d86](01d3d86))
* Support pre-release versions in update checker
([#2164](#2164))
([e18e9dc](e18e9dc))
* Surface clear error for missing sandbox provider deps
([#1999](#1999))
([939f56a](939f56a))
* Use relative paths in langgraph config for Windows compat
([#2244](#2244))
([d10dfbd](d10dfbd))
* Warn agent that local filesystem is inaccessible in sandbox mode
([#2274](#2274))
([a3b61e5](a3b61e5))
* Wire `enable_ask_user` flag to remove tool in non-interactive mode
([#2105](#2105))
([2399747](2399747))

### Performance Improvements

* Sub 250ms first paint
([#2027](#2027))
([e42e05c](e42e05c))
* Defer `/model` selector data loading off event loop
([#2259](#2259))
([a32ce7f](a32ce7f))
* Defer heavy imports from startup path
([#2022](#2022))
([b7f5a99](b7f5a99))
* Defer pydantic and adapter imports out of startup hot path
([#2269](#2269))
([0a410b4](0a410b4))
* Prewarm markdown stack and cache skill body render
([#2236](#2236))
([0a3ba47](0a3ba47))
* Reduce health poll interval for local langgraph dev server
([#2283](#2283))
([7f5c3de](7f5c3de))

---

_Everything above this line will be the GitHub release body._

---

> [!NOTE]
> A **New Contributors** section is appended to the GitHub release notes
automatically at publish time (see [Release
Pipeline](https://github.com/langchain-ai/deepagents/blob/main/.github/RELEASING.md#release-pipeline),
step 2).

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Mason Daugherty <[email protected]>