[diff view] RFC 005 3/4: environment runtime - #2
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…idge Makes the RFC 005 types runnable: an environment that owns a harness subprocess, hands it the environment's MCP tools, and turns each step() into one conversational turn. - `environment.py`: `HarnessAction` + `HarnessEnvironment(MCPEnvironment)`. reset() stops any live harness, enumerates and conflict-resolves the env tools, starts the bridge, injects, then starts the harness -- injection strictly before start, per the RFC. step() runs one turn; MCP actions keep their normal routing. Rubrics run after the turn completes, outside the harness's control loop, preserving RFC 004's reward boundary. - `process.py`: `HarnessProcess`, a loop-agnostic Popen + reader-thread helper (readiness gating, stderr-tail diagnostics, idempotent stop with SIGTERM -> SIGKILL escalation over the process group). - `bridge.py`: `HarnessMCPBridge`, serving the env's FastMCP tool surface over loopback HTTP for the harness to consume. Three decisions worth reviewer attention: 1. `HarnessEnvironment` subclasses `MCPEnvironment` and substitutes an empty internal FastMCP when `mcp=None`. `MCPEnvironment` requires `mcp_server` positionally, so the RFC's optional-mcp constructor cannot be written literally; this keeps reserved-name validation, tool enumeration and mcp_session() integration for free. 2. Popen + threads rather than asyncio subprocess transports, because the same instance must work across event loops: the sync facade spins a fresh loop per call (run_async_safely) while the server keeps one long-lived loop. Asyncio subprocess transports are bound to their creating loop. 3. The bridge is a separate loopback server rather than a reuse of the env server's /mcp endpoint. Reusing /mcp would put the orchestration routes (/reset, /step, /state) on the same origin the harness can reach, violating the RFC's security boundary; it would also hand the harness a *different* env instance, since WS /mcp creates its own session. Keeping it separate makes the boundary structural rather than filter-based. Turn timeouts and harness crashes become terminal observations (done=True, metadata.error_type) rather than exceptions, so a training loop scores the episode and moves on instead of unwinding. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Closing: this was only a diff view, and an un-mergeable PR in the list is more confusing than the cumulative diff it was working around. Review happens on the upstream PR. |
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Incremental-diff view for huggingface/OpenEnv#1099.
Review and discussion happen upstream — this PR exists only because cross-fork PRs cannot chain bases, so the upstream one has to target
mainand its "Files changed" tab includes the PRs beneath it in the stack.Here the base is
rfc-005/pr2-harness-foundation-types, so Files changed shows exactly this step's diff (commitf3d90c21) and nothing else.Not for merging: merging it into the fork would desync the stack.
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