{
  "schema_version": "1.3.0",
  "slug": "when-does-a-per-hop-retry-budget-amplify-a-transient-slowdown-into-a-sustained-outage",
  "title": "When does a per-hop retry budget amplify a transient slowdown into a sustained outage?",
  "date_of_record": "2026 November 1",
  "scope": "Applies to synchronous call chains where each hop retries independently with its own counter, and where no end-to-end deadline is propagated. Excludes single-hop clients, and chains that carry a deadline header consumed by every hop.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-does-a-per-hop-retry-budget-amplify-a-transient-slowdown-into-a-sustained-outage.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-does-a-per-hop-retry-budget-amplify-a-transient-slowdown-into-a-sustained-outage.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-does-a-per-hop-retry-budget-amplify-a-transient-slowdown-into-a-sustained-outage.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 965,
    "python_slice_tokens": 118,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "**Predicate.** With H hops and R retries per hop, worst-case fan-out at the terminal service is (1 + R)^H. Retrying is safe if and only if (1 + R)^H <= terminal_capacity_slack, where slack is the multiple of normal load the terminal service can absorb while degraded. **Failure.** Each hop sees a local failure and does the locally correct thing. No hop sees t...",
    "what_was_observed": "**Signature.** Terminal service CPU at saturation. Inbound RPS rising with no change in user traffic. Each upstream reports a modest retry rate (2 to 4 percent). Latency climbing at every hop simultaneously. **Trace.** H=4, R=3, so 256 worst-case arrivals per user request. A single slow dependency at p99.9 pushes each hop's retry rate from 0.1 to 3 percent. Fan-out at the terminal rises from 4 to roughly 4 * (1.03)^4...",
    "condition_of_validity": "Per-hop retrying is valid only while at least one holds: 1. **Deadline.** A single absolute deadline is propagated and consumed by every hop, so total wall-clock work per user request is bounded regardless of retry count. 2. **Budget.** Retries are drawn from a shared, cross-hop token budget sized to terminal slack, not counted per hop. 3. **Blast radius.** ...",
    "decision_boundary": "- (1 + R)^H <= slack and no deadline: safe under normal conditions, unsafe under a correlated failure. Treat as degraded. - (1 + R)^H > slack: retry amplification is arithmetically guaranteed during any correlated slowdown. Do not ship. - Deadline propagated: safe regardless of R and H, because the deadline bounds total work. - Retry budget shared across hop...",
    "operational_effect": "The failure is a property of the composition, not of any service, so no service owner is positioned to fix it. Remediation is a protocol change: an absolute deadline header consumed at every hop, with retries permitted only while budget remains. The trap is to lower R at the noisiest hop. That reduces fan-out by a constant factor while leaving the product un..."
  },
  "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": "0baedd9339e26d0451955bb1d9a829d5c155a9bf3cd65337d02a087d9160d1a8",
    "verified_classes": [
      "RetryAmplificationError",
      "RetryBudgetGate"
    ],
    "verified_functions": [
      "dispatch_retry_policy",
      "verify"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "RetryAmplificationError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}