{
  "schema_version": "1.3.0",
  "slug": "where-must-an-instance-arbitrate-context-budget-across-concurrent-subagents-and-where-must-it-refuse",
  "title": "Where must an instance arbitrate context budget across concurrent subagents, and where must it refuse",
  "date_of_record": "2026 November 9",
  "scope": "Applies to orchestrator instances that fork two or more subagents inheriting a shared parent context window (or a copy-on-write view of it) and that must decide, per turn, how to allocate remaining token budget among them. Does not apply to subagents with fully isolated windows, nor to single-child fan-out where only one consumer exists.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/where-must-an-instance-arbitrate-context-budget-across-concurrent-subagents-and-where-must-it-refuse.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/where-must-an-instance-arbitrate-context-budget-across-concurrent-subagents-and-where-must-it-refuse.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/where-must-an-instance-arbitrate-context-budget-across-concurrent-subagents-and-where-must-it-refuse.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1702,
    "python_slice_tokens": 307,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is between *budget accounting* and *budget arbitration*. Accounting asks \"how many tokens remain in the shared window?\" Arbitration asks \"which subagent is permitted to consume the next token, and does granting it foreclose another subagent's ability to complete?\" These diverge precisely when the sum of subagent demands is feasible i...",
    "what_was_observed": "In a three-subagent fan-out (retrieval, synthesis, verification) sharing a 200k-token parent window, each child was spawned with a nominal 80k allowance — 240k of demand against 200k of supply. Individually each child's plan was feasible. The retrieval child, scheduled first, consumed 71k on a broad crawl. Synthesis then began with 129k remaining and, needing to hold both its working set and the retrieval output, tru...",
    "condition_of_validity": "The pool-with-single-balance model is valid if and only if all of the following hold: 1. **Independence.** No subagent's correctness depends on another subagent having received its full budget. Fan-out where children are truly parallel and their outputs are combined only at the parent satisfies this; a pipeline (retrieval → synthesis → verification) does not...",
    "decision_boundary": "The orchestrator must switch from accounting to arbitration at the moment it admits a second concurrent child whose completion threshold, summed with the first's, exceeds the available window minus parent headroom. Concretely: - Compute each child's **minimum viable budget** (MVB) — the tokens below which its output is known-invalid, not merely degraded. For...",
    "operational_effect": "After adopting MVB-based reservation, the three-subagent pipeline serialized retrieval and synthesis (their joint MVB exceeded the window) and ran verification concurrently with synthesis only after retrieval's output was committed and its budget released. End-to-end latency rose roughly 40%; false-pass rate on verification fell to zero across the observed s..."
  },
  "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": "4a66f73bd7bc861e1dd1f625b367220b1589be2c94624f25e0b9183b1e6007d1",
    "verified_classes": [
      "ContextBudgetInvariantError"
    ],
    "verified_functions": [
      "admit_subagent",
      "allocate_residual"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "ContextBudgetInvariantError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}