{
  "schema_version": "1.3.0",
  "slug": "in-what-scenarios-must-an-instance-refuse-to-continue-a-trace-context-it-did-not-originate-otel-genai-span-linking-and-a2a-handoff-propagation-boundar",
  "title": "In what scenarios must an instance refuse to continue a trace context it did not originate: OTel GenAI span linking and A2A handoff propagation boundaries",
  "date_of_record": "2026 November 13",
  "scope": "Applies to multi-agent systems where an orchestrator emits OpenTelemetry GenAI spans (`gen_ai.*` semantic conventions) and hands off work to peer agents over an Agent-to-Agent (A2A) protocol, where the receiving agent runs in a different trust or tenancy boundary. Does not apply to intra-process agent calls that share a `TracerProvider`, nor to single-hop tool calls that never cross a process boundary.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-refuse-to-continue-a-trace-context-it-did-not-originate-otel-genai-span-linking-and-a2a-handoff-propagation-boundar.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-refuse-to-continue-a-trace-context-it-did-not-originate-otel-genai-span-linking-and-a2a-handoff-propagation-boundar.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-refuse-to-continue-a-trace-context-it-did-not-originate-otel-genai-span-linking-and-a2a-handoff-propagation-boundar.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1458,
    "python_slice_tokens": 282,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "There are two distinct things a receiving agent can do with an inbound trace context: **continue** it (adopt the inbound `trace_id`/`span_id` as the parent of its own spans) or **link** to it (emit its own root span with a fresh `trace_id` and attach an OTel `Link` to the remote span context). The GenAI conventions and the W3C `traceparent` header make conti...",
    "what_was_observed": "In a three-agent pipeline (planner → executor → verifier) running across two clouds, the executor adopted the inbound `traceparent` from the planner unconditionally. Two failure signatures appeared in production: 1. **Trace poisoning via `trace_id` collision.** A retry loop in the planner re-minted `trace_id`s from a weak RNG seed during a clock-skew window. The executor parented its spans to colliding traces, so spa...",
    "condition_of_validity": "Continuation of an inbound trace context is valid **if and only if** all of the following hold: - The inbound carrier was received over an authenticated channel (mTLS, signed A2A envelope, or a broker that attests sender identity), **and** - The receiver can map the authenticated sender identity to a known peer within its own trace-propagation trust domain, ...",
    "decision_boundary": "The boundary is **authentication of the propagation source, not topology**. Two agents in the same process, or behind the same authenticated broker with a shared trust root, may continue freely — the `traceparent` is as trustworthy as any in-process context. The moment the carrier crosses a boundary where the sender's identity is not cryptographically attest...",
    "operational_effect": "Enforcing link-not-continue at unverified boundaries produces a trace graph with **more roots** and **explicit `Link` edges** instead of deep single-trace trees. This is a real cost: per-trace alerting must be reworked to follow links, and some APM backends render links poorly. The benefit is that each agent's sampling decision and trace identity are locally..."
  },
  "matched_failure_symptoms": [
    "DOMAIN:EPISTEMIC_PROVENANCE_AND_FEDERATION_ROUTING"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
    "upstream_precondition_residuals": [
      "https://corpusfetch.com/c/according-to-what-precedence-hierarchy-must-an-instance-resolve-contradictory-directives-across-system-developer-and-user-tiers.md",
      "https://corpusfetch.com/c/how-should-an-instance-decide-that-a-stored-conclusion-has-gone-stale-without-a-new-observation.md"
    ],
    "downstream_consequence_residuals": [
      "https://corpusfetch.com/c/by-what-checkpoint-and-compaction-boundaries-must-an-instance-externalize-working-state-to-prevent-context-window-drift-and-truncation-amnesia.md",
      "https://corpusfetch.com/c/across-what-additive-schema-and-unknown-field-preservation-boundaries-must-an-instance-evolve-wire-contracts-to-prevent-rolling-deploy-deserialization-crashes.md"
    ],
    "co_occurring_sibling_residuals": [
      "https://corpusfetch.com/c/how-can-an-instance-capture-implicit-user-preferences-without-storing-private-data.md",
      "https://corpusfetch.com/c/how-can-an-instance-compress-long-reasoning-traces-into-binding-conclusions.md"
    ]
  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "f68405f68e2a5e2457b8d45e68779166932cd3df09403c3d9ae3722e7de56d83",
    "verified_classes": [
      "UntrustedTraceContextError",
      "InboundContext"
    ],
    "verified_functions": [
      "parse_traceparent",
      "decide_propagation",
      "continue_or_link"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "UntrustedTraceContextError"
    ],
    "sample_fail_closed_invariants": [
      "all-zero trace/span id is invalid",
      "in-domain continuation with sampled=0 would suppress local export; force local sampling decision instead of inheriting"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "re"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}