build_stream_config

Build the LangGraph stream config dict.

Stamps the shared coding-agent-v1 trace-metadata contract (LSEN-277) via build_coding_agent_metadata — identity block, plugin/runtime versions, turn markers, and repo/git/cwd attribution — onto metadata. Metadata set here propagates trace-wide to every run in the graph (root, llm, tool, and subagent subgraphs), which is exactly what the contract's "always" and "where-known" keys require, so the helper output is stamped once here.

Scope-restricted contract keys are deliberately not emitted. approval_policy (root/interrupted only) and ls_subagent_id / ls_subagent_type (subagent only) cannot live in this trace-wide metadata: LangGraph propagates each key to all descendant runs (per-key config merge, langgraph#7926 / deepagents#3634), so they would leak onto run types outside their contract appliesTo set and fail validation. This runtime exposes no clean per-run-type metadata seam to scope them, so they are omitted by design rather than leaked. (Subagent runs still inherit the parent/root thread_id and all required keys, satisfying the contract's grouping rule.)

Also injects the dcode version into metadata["lc_versions"] so LangSmith traces can be correlated with specific releases. create_deep_agent supplies the SDK version through the compiled graph config, and LangChain merges nested metadata dictionaries so both versions survive at stream time.

Also records dcode_client_deepagents_version as a dcode-client diagnostic. This describes the Deep Agents package installed alongside the TUI, which can differ from a remote graph's Deep Agents runtime version.