Best possible solution:

Land this after maintainers explicitly accept the bounded response-byte metric semantics, or preserve the old estimate under a separate metric if existing observability consumers need it.

Do we have a high-confidence way to reproduce the issue?

Yes from source inspection: current main serializes the snapshotless delta event shape for response byte accounting, while the PR head counts the incremental delta string. I did not run a live long-running local-model reproduction in this read-only review.

Is this the best way to solve the issue?

Yes, this is the best scoped fix for the diagnostic accounting path: it changes the central embedded-stream diagnostic wrapper and updates the exported docs/OTEL description using the existing stream event contract. The remaining question is compatibility acceptance for the changed metric baseline, not a better code location.

AGENTS.md: found and applied where relevant.

Codex review notes: model gpt-5.5, reasoning high; reviewed against 5b84ebfc56c9.

Label changes:

• add rating: 🐚 platinum hermit: Overall readiness is 🐚 platinum hermit; proof is 🌊 off-meta tidepool and patch quality is 🦞 diamond lobster.
• remove rating: 🦞 diamond lobster: Current PR rating is rating: 🐚 platinum hermit, so this older rating label is no longer current.

Label justifications:

• P1: This PR targets the P1 dense local-provider stream responsiveness work by removing repeated diagnostic serialization from hot model stream deltas.
• merge-risk: 🚨 compatibility: Merging changes the observable byte values for responseStreamBytes and openclaw.model_call.response_bytes, which can affect existing dashboards, thresholds, and plugin hook consumers.
• rating: 🐚 platinum hermit: Overall readiness is 🐚 platinum hermit; proof is 🌊 off-meta tidepool and patch quality is 🦞 diamond lobster.
• status: 👀 ready for maintainer look: ClawSweeper has no concrete contributor-facing blocker left for this PR. Not applicable: The external-contributor real-proof gate is not applicable to this maintainer PR; the PR body still records focused tests, docs/lint checks, and an AWS Crabbox changed gate, with a live long-running local-model session left untested.

PR surface:

Source +18, Tests -11, Docs +2. Total +9 across 5 files.

What I checked:

• Current main still uses event-shape byte accounting: On current main, responseStreamChunkByteLengthUnchecked removes partial but then serializes the remaining chunk shape for byte accounting, so text_delta contributes JSON event bytes rather than only the text delta bytes. (src/agents/embedded-agent-runner/run/attempt.model-diagnostic-events.ts:112, 5b84ebfc56c9)
• PR counts high-frequency deltas directly: On the PR head, streamDeltaByteLength handles text_delta, thinking_delta, and toolcall_delta with string delta values before the fallback partial-stripping path. (src/agents/embedded-agent-runner/run/attempt.model-diagnostic-events.ts:116, 347f5430ac5c)
• Stream event contract supports the delta-only path: The shared AssistantMessageEvent contract defines text, thinking, and tool-call delta events with delta: string plus an accumulated partial, matching the PR's predicate. (packages/llm-core/src/types.ts:369, 5b84ebfc56c9)
• Runtime caller is the embedded model stream wrapper: The embedded attempt runner wraps the provider stream with wrapStreamFnWithDiagnosticModelCallEvents, so the changed accounting sits at the central diagnostic observation point for model stream chunks. (src/agents/embedded-agent-runner/run/attempt.ts:2807, 5b84ebfc56c9)
• Exported metric surface consumes the changed value: The OTEL plugin records responseStreamBytes into openclaw.model_call.response_bytes, making the byte baseline an externally visible diagnostics/observability surface. (extensions/diagnostics-otel/src/service.ts:390, 5b84ebfc56c9)
• Regression coverage matches the intended behavior: The PR-head test asserts dense text_delta accounting does not serialize a large partial snapshot and expects responseStreamBytes to equal Buffer.byteLength("abc", "utf8"). (src/agents/embedded-agent-runner/run/attempt.model-diagnostic-events.test.ts:360, 347f5430ac5c)

Likely related people:

• vincentkoc: Authored the PR commits for this diagnostic accounting change and also carried the related merged Ollama dense-stream yield fix referenced from the same root issue. (role: recent area contributor and current PR implementer; confidence: high; commits: 311f49ad5adb, 347f5430ac5c, c7b190beec73; files: src/agents/embedded-agent-runner/run/attempt.model-diagnostic-events.ts, src/agents/embedded-agent-runner/run/attempt.model-diagnostic-events.test.ts, docs/logging.md)
• joshavant: Current-main blame in this checkout points the existing diagnostic accounting helper, OTEL metric description, and related docs to a broad commit by this author, so they are a useful routing signal for the current baseline. (role: current-main source provenance; confidence: medium; commits: fbaa5a6f0a57; files: src/agents/embedded-agent-runner/run/attempt.model-diagnostic-events.ts, extensions/diagnostics-otel/src/service.ts, docs/logging.md)
• osolmaz: Provided maintainer context that this PR is split out from the broader dense-stream work and should preserve the reviewer and attribution history from the closed broader branch. (role: related split-stack contributor; confidence: medium; commits: aac174b329d4; files: src/agents/embedded-agent-runner/run/attempt.model-diagnostic-events.ts, src/agents/runtime/proxy.ts, src/plugin-sdk/provider-stream-shared.ts)

• 🦀 challenger crab: rare, exceptional readiness with strong proof, clean implementation, and convincing validation.
• 🦞 diamond lobster: very strong readiness with only minor maintainer review expected.
• 🐚 platinum hermit: good normal PR, likely mergeable with ordinary maintainer review.
• 🦐 gold shrimp: useful signal, but proof or patch confidence is still limited.
• 🦪 silver shellfish: thin signal; proof, validation, or implementation needs work.
• 🧂 unranked krab: not merge-ready because proof is missing/unusable or there are serious correctness or safety concerns.
• 🌊 off-meta tidepool: rating does not apply to this item.

Shiny media proof means a screenshot, video, or linked artifact directly shows the changed behavior. Runtime, network, CSP, and security claims still need visible diagnostics.

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