[JasonW404]

Adds an opt-in NEXENT_AGENT_RUNTIME=toolcalling runtime based on smolagents ToolCallingAgent alongside the default CodeAgent. Existing authorized tools work as native calls and as prebound functions inside optional restricted code_execution; persisted Agent Definitions require no migration.

The native loop owns structured provider history, streamed call assembly and correlated results. It reuses Nexent model configuration/retries/concurrency, tool factories, sandbox lifecycle/bridge, context selection, observer events and tracing. NL2Agent/NL2Skill retain CodeAgent for their platform authoring protocols.

Validation:

• 979 relevant unit tests passed in isolated module runs; the two new runtime modules have 99.10% statement and 94.90% branch coverage locally.
• 17 real-service D3 checks passed: local/Docker direct, code, programmatic and hybrid paths; four provider families; MCP; managed child; error recovery; step limits; live stream cancellation.
• 3 deployed HTTP/SSE checks and 1 branch-image/source/health check passed. Built-in-browser hybrid debug verified separately.
• The same persisted Agent completed plain/hybrid workloads under both runtime selections. Phoenix MCP inspection verifies native histories and nested tool spans. Immutable image/source identities and sanitized evidence are under docs/experimental-native-runtime/evidence/.

This remains an architecture spike, not production parity. Native current-run compaction and multimodal projection are incomplete; dynamic MCP container journeys, live planning/verifier/clarification journeys and concurrent child lifetimes remain unverified. Provider reasoning controls/fields are recorded independently from tool support, including inconsistent gateway observations. Both runtimes retain the existing unauthenticated-run HTTP 500 defect while denying execution.

Based on remote tag v2.8.4 (c43d2d995b15c9005c0d736cd60200a22305de74). Final experimental deployment stays on the host by explicit user preference; Nexent-Test remains stopped. Investigation, design, compatibility, validation and develop migration findings are included in the five runtime documents. No production migration or dependency upgrade is proposed.

Current test-only head is 1ba6aa0a490945dd92a510e877b16ea7b4293222. Tested product source matches commit 128f22ee1d45e89ae77e8029544a1add37a5e562; final main image sha256:cd0e5604e99984eb0f21db8c01703100861387183299538f923247f0b37a51e5. Existing CI filters omit main-targeted PRs; equivalent branch workflows were dispatched manually without configuration changes.

Final CI on 1ba6aa0a4: unit tests and coverage upload, amd64/arm64 image builds, changed-source copyright checks and CodeQL passed. Codecov PR report reports 96.96312% patch coverage, above the workspace 90% gate; 4 missing and 10 partially covered lines remain in the native loop. No full production parity is claimed.

[codecov]

Codecov Report

❌ Patch coverage is 96.96312% with 14 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
sdk/nexent/core/agents/native_runtime.py	96.74%	4 Missing and 10 partials ⚠️

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