Add SWE debug environment

[rasdani]

Summary

• add SWEDebugEnv, a no-agent staged debugger for SWE-style SandboxTaskSet instances
• support optional task setup, one debug_step (none, gold_patch, command, script), and optional test/scoring at exit
• export SWEDebugEnv from the experimental composable modules

Validation

• uv run pytest tests/test_swe_debug_env.py -q
• uv run ruff check verifiers/envs/experimental/composable/swe_debug_env.py tests/test_swe_debug_env.py
• push hooks: ruff check, ruff format, ty (ci parity)

---

Note

Medium Risk
Adds a new sandbox-orchestrating environment that can execute arbitrary debug commands/scripts and short-circuit test runs, which could affect resource usage and failure classification. Also changes Multi-SWE dataset construction by no longer excluding C/C++ rows, potentially impacting evaluation mix and runtime.

Overview
Adds SWEDebugEnv, a no-agent experimental environment that creates a SWE-style sandbox, optionally runs task setup, performs one configurable debug step (none, gold_patch, command, script), and optionally runs/scoring tests, recording timing and output tails plus standardized failure reasons.

Exports SWEDebugEnv via the experimental __init__ modules and adds focused pytest coverage for the pipeline and failure handling. Separately updates MultiSWETaskSet to stop filtering out C/C++ tasks during dataset build.

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[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Falsy check on debug_timeout ignores explicit zero

Low Severity

The expression self.debug_timeout or self.test_timeout uses Python's or operator, which treats 0 as falsy. If a caller explicitly passes debug_timeout=0, it will be silently ignored and self.test_timeout (default 900) will be used instead. The correct pattern for an int | None optional is self.debug_timeout if self.debug_timeout is not None else self.test_timeout.

 

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[cursor]

New environment class missing documentation updates

Low Severity

SWEDebugEnv is a new user-facing environment class exported from the experimental composable module, but no documentation files are updated. The docs/environments.md file describes the composable module's classes (ComposableEnv, TaskSet, SandboxTaskSet, Harness, SandboxSpec) under the experimental section, and docs/reference.md lists environment classes. The new SWEDebugEnv class is not mentioned in either. This violates the rule requiring documentation updates when adding core user-facing functionality described in docs/.

 

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