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How a native session binds to an OpenClaw session and mirrors into its transcript, and how tool, media, terminal-outcome, and settled-turn results come back through the attempt result. Part of the Agent harness plugins reference.

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Native sessions and transcript mirror

A harness may keep a native session id, thread id, or daemon-side resume token. Keep that binding explicitly associated with the OpenClaw session, and keep mirroring user-visible assistant/tool output into the OpenClaw transcript. The OpenClaw transcript remains the compatibility layer for:
  • channel-visible session history
  • transcript search and indexing
  • switching back to the built-in OpenClaw harness on a later turn
  • generic /new, /reset, and session deletion behavior
For user-message mirrors, use restorePreparedUserTurnOperationalMetaForRuntime({ runtimeMessage, preparedMessage }) from openclaw/plugin-sdk/agent-harness-runtime. Pass an independent, trusted snapshot of the host-prepared input as preparedMessage. Clone content and selected-mention metadata before hooks that can mutate them in place, and keep that snapshot unchanged. The helper restores operational metadata on user messages without replacing native or hook-rewritten content. Non-user runtime messages are returned unchanged. Human mentions survive only when the entire content value exactly matches the prepared snapshot; changed text must not inherit the old selections. Restored metadata neither authorizes actions nor proves a fresh transcript append. After the canonical append, pass its committed message, anchor, and actual { appended } result to userTurnTranscriptRecorder.markRuntimePersisted(...). Only appended: true can trigger an original-input commit notification; an idempotent history match must report false. Store native bindings in plugin state. Implement reset(...) for an in-place session reset and withSessionDeletion(params, run) for removal of a session key, including expiry and maintenance. A physical session ID changing at the same key is a transfer, not deletion; preserve any compaction adoption path. withSessionDeletion acquires the native owner’s lease before calling run({ commit, rollback }). Core invokes the synchronous commit() at the session row deletion boundary and rollback() if the transaction fails. Rollback must also tolerate a failed or unapplied commit. Keep asynchronous subscription cleanup after run so it does not hold the SQLite writer queue; do not restore bindings for errors after the session transaction committed. Recheck params.assertCurrent() after awaited work and immediately before mutating native state. The callback belongs to one registered harness lifetime; retaining it after the operation closes does not retain authority. Post-delete hooks are notifications, not the owner of durable binding removal.

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Tool and media results

Core constructs the OpenClaw tool list and passes it into the prepared attempt. When a harness executes a dynamic tool call, return the tool result back through the harness result shape instead of sending channel media yourself. This keeps text, image, video, music, TTS, approval, and messaging-tool outputs on the same delivery path as OpenClaw-backed runs. Set AgentHarnessAttemptResult.hostOwnedToolMediaUrls only for native artifacts that the trusted harness runtime created and persisted itself. Every entry must also appear in toolMediaUrls. Never include model-selected dynamic-tool or OpenClaw-tool media. On message_tool_only routes, this narrow provenance lets native runtime artifacts survive source-reply suppression; normal send policy and ambient-room admission still apply.

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Terminal tool outcomes

AgentHarnessAttemptParams.observeToolTerminal is the host-owned terminal outcome accumulator. A harness that executes OpenClaw dynamic tools or native tools must call it when each tool reaches one terminal outcome, before the attempt result is finalized. Harnesses that do not execute tools do not need to call it. Report facts from the execution boundary:
  • Pass the protocol call id when one exists, the canonical tool name, and the arguments that actually reached the tool after preparation or hook rewrites.
  • Pass the original host tool result or thrown error as result. Core reads private effect provenance from that object; serialized fields cannot provide this proof. Preserve internal result state when projecting a host result.
  • Set executionStarted: false when validation, approval, or another guard stopped the call before the tool implementation began. Once dispatch may have happened, report true conservatively.
  • Report outcome: "success" or outcome: "failure". Include the structured failure fields available from the runtime instead of inferring failure from display text.
  • Use nativeMutation only for native tools that do not use an OpenClaw tool definition. Supply protocol-owned mutation and replay facts there; do not copy OpenClaw’s mutation classifier into the harness.
The callback returns the canonical resolution for that call. Carry its lastToolError into AgentHarnessAttemptResult and use its execution, arguments, and side-effect facts in the harness projection instead of deriving parallel state. The host keeps an unresolved mutating failure across unrelated successful tools and clears it only after the matching action succeeds. The callback remains optional for source compatibility with older experimental harnesses. Optional does not mean ignorable for a harness that executes tools: without terminal reports, OpenClaw cannot preserve mutating-tool failure truth across later tool calls, including quiet heartbeat completion.

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Settled tool finalization

OpenClaw may need one final visible answer after a harness has completed every tool call but its native turn ended without assistant text. A harness can opt into that recovery by implementing finalizeSettledTurn({ attempt, settledAttempt }). The callback is a separate capability, not another ordinary attempt. It must:
  • use either the exact restricted native transcript or a complete application transcript frozen through the settled tool-result boundary;
  • expose no tools, permission-grant or user-input capabilities, native execution hooks, agents, skills, memory, scheduling, extensions, or remote control;
  • send only the host-provided finalization prompt; and
  • fail closed if its selected transcript/isolation strategy cannot enforce those restrictions.
OpenClaw invokes the callback once as a terminal sub-operation, outside the ordinary attempt and retry loop. A failure ends the run with the side-effect-aware incomplete-turn warning; it cannot enter ordinary auth/profile rotation, model fallback, context recovery, compaction continuation, or hook-requested revision paths. Finalization also skips plugin prompt mutation, before_agent_run, LLM input/output, terminal revision, and agent_end hooks. Core diagnostics still record the operation and its failure. The callback returns AgentHarnessSettledTurnFinalizationResult, not an ordinary attempt result. Its public fields are limited to the completed assistant message, finalization-call usage, transcript-ownership metadata, and diagnostic trace. Tool, delivery, media, spawn, lifecycle, replay, session, and fallback state cannot cross this result boundary. Unknown fields and assistant tool calls fail closed. A harness that internally reuses its full attempt engine can call projectSettledTurnFinalizationAttemptResult(...) before returning. The helper rejects canonical failure, tool, delivery, replay, and lifecycle evidence, then projects only the narrow result. It is defense in depth after native isolation, not a substitute for removing the native capability surface. A projection-backed harness must capture the active branch after the settled turn is mirrored and prove that the current prompt and every current tool call/result are present through that boundary. Put the frozen evidence on settledAttempt.settledTurnFinalizationContext as one of:
  • source: "openclaw-transcript" with messages: the complete application transcript through the boundary.
  • source: "harness" with data: an immutable, bounded projection interpreted only by the owning harness. Core passes this opaque value through; the finalizer must verify its own context type before using it.
  • source: "unavailable": the harness permits finalization for this settled turn, but safe replay evidence could not be captured. The finalizer must reject this state before provider or native I/O; core can still use its existing host-owned fallback without repeating tools.
The unavailable state records eligibility, not validated history. Eligible capture failures, including missing, drifting, or oversized evidence, can reach that no-model fallback. Do not emit it for failures the harness excludes from finalization, such as authentication or usage-limit errors. Command-only harnesses must retain the attributed assistant tool-call entry in messagesSnapshot; the host fallback can use that settled-batch identity when visible-assistant fields are absent. Enforce projection limits while acquiring messages, rather than cloning the whole transcript before checking its size. Successful capture must finish all identity and source-evidence checks before returning the attempt. Do not retain an open transcript reader in data. The finalizer must reject a missing, unsupported, ambiguous, or oversized context. It must not truncate messages, drop earlier history, or describe an application projection as exact native history. Harnesses that resume one restricted native session do not need this projection field. Do not implement this callback by calling runAttempt with a best-effort disableTools hint. The harness owner must enforce the complete native capability boundary. OpenClaw does not provide a generic fallback because it cannot attest that an arbitrary native runtime honored those restrictions. The callback remains optional for experimental third-party harness compatibility. When the selected harness omits it, OpenClaw preserves the existing incomplete-turn error instead of risking repeated side effects.