{"schema_version":1,"experiment_id":"eoa_inverse_innovation_exp09_archetype_breadth150_20260804","cell_id":"disequilibrium_leverage_and_dissipation_management__computer_science","arm":"BREADTH_PROBE_ONE_SHOT","candidate_id":"disequilibrium_leverage_and_dissipation_management__computer_science__P1","proposal_index":1,"version":0,"title":"Hot-Flow-Driven Shadow Splitting for a Skewed Key-Value Shard","problem":"During a flash crowd, requests for one key prefix overload a shard. Adding generic capacity or shedding load can protect the service but does not construct the workload-adapted partition needed after the surge, while a full scan-and-copy reshard consumes capacity precisely when the shard is stressed. The temporary concentration of reads is both a hazard and a representative traversal of the data that most urgently needs relocation.","actors":["Clients generating the flash-crowd reads","Tenants sharing the storage cluster","On-call site reliability engineer","Storage service owner","Automated shard controller"],"observable_state":"One shard's request queue, CPU, or tail latency rises above its steady-state range while sibling shards retain capacity; a bounded set of key prefixes accounts for the skew; sampled requests can be shadowed; and duplicate-read, network, storage, error, and latency costs can be measured separately from normal traffic.","consequence":"If the service only throttles, scales, or waits, the surge may be dissipated as rejected requests and operational load without producing a better partition. If it starts an unconstrained migration, duplicate work can worsen the hotspot, pollute caches, create inconsistent copies, or trigger oscillating split decisions.","affected_objective":"Maintain client availability and latency while converting a transient hot-prefix surge into a verified, workload-adapted shard split that can remain useful after the surge.","intervention":"When a bounded hot-prefix gradient is detected, admit a small sample of eligible reads into a shadow-split channel. Each admitted read lazily copies or verifies the requested record on its candidate destination shard and records routing correctness, thereby using the live hot flow to construct and validate the hot working set rather than performing an immediate full scan. Cap sampling rate, migration bandwidth, affected prefixes, and duration; charge all duplicate work to a dissipation budget; damp coupling as source-shard stress rises; and automatically decouple if latency, errors, consistency mismatches, or queue growth cross stop thresholds. Promotion of the candidate routing map remains a separate human-authorized decision after re-equilibration review.","structural_mapping":[{"archetype_element":"Equilibrium Baseline","domain_realization":"The normal shard layout, request distribution, queue depth, and latency range before the flash crowd."},{"archetype_element":"Disequilibrium Source","domain_realization":"The temporary concentration of live reads on a recognizable key prefix while other shards retain capacity."},{"archetype_element":"Controlled Coupling Channel","domain_realization":"A rate-limited sampler that turns eligible hot reads into lazy copy-and-verify operations against candidate split shards."},{"archetype_element":"Operating Window","domain_realization":"Explicit limits on sampled traffic, prefixes, migration bandwidth, duration, source-shard headroom, and candidate-shard exposure."},{"archetype_element":"Dissipation Budget","domain_realization":"A ledger for added source reads, network bytes, destination writes, verification CPU, cache pollution, operator attention, and cleanup work."},{"archetype_element":"Runaway Feedback Monitor","domain_realization":"Near-real-time monitoring of tail latency, queue slope, retry rate, mismatch rate, destination saturation, and repeated split/merge signals."},{"archetype_element":"Decoupling and Re-Equilibration Rule","domain_realization":"Set the sampling rate to zero on any stop condition or when the hot gradient expires; retain the original routing map until a reviewed promotion decision."},{"archetype_element":"Waste or Entropy Sink","domain_realization":"A bounded migration queue and disposable shadow namespace that contain incomplete copies and can be garbage-collected without altering authoritative records."},{"archetype_element":"Gradient Replenishment Check","domain_realization":"Confirm that admitted hot reads continue to cover uncopied or unverified records; taper when requests mostly repeat completed work."},{"archetype_element":"Stakeholder Harm Boundary","domain_realization":"Normal client requests and unrelated tenants may not lose reserved capacity or receive weaker consistency guarantees to accelerate the shadow split."}],"mechanism_mapping":[{"mechanism_slug":"gradient_and_flux_map","role":"Map request volume and key-prefix flow across source and candidate shards so only a specific, measurable hotspot drives the split.","counterfactual_removal":"Without the map, ordinary noise or diffuse overload could trigger copying that has no useful directional target."},{"mechanism_slug":"dissipation_ledger","role":"Account for duplicate reads, writes, bytes, cache displacement, cleanup, and operator load against fixed budgets.","counterfactual_removal":"Without the ledger, apparent migration progress could conceal SLO harm or displaced cost to sibling tenants."},{"mechanism_slug":"bounded_coupling_pilot","role":"Start with one shadow prefix and a low sampling ceiling before permitting any broader coupling.","counterfactual_removal":"Without the pilot, the full hot stream could immediately amplify the source-shard overload."},{"mechanism_slug":"runaway_stop_rule","role":"Force sampling to zero when latency, errors, queue growth, consistency mismatches, or destination saturation breach predetermined thresholds.","counterfactual_removal":"Without an automatic stop, delayed human reaction could allow positive feedback between duplication, retries, and overload."},{"mechanism_slug":"damping_and_venting_controls","role":"Reduce sampling as source headroom falls and drain excess candidate work into a bounded queue that rejects new shadow tasks before delaying client traffic.","counterfactual_removal":"Without damping and venting, the useful channel could compete directly with authoritative requests during the sharpest part of the surge."},{"mechanism_slug":"post_gradient_re_equilibration_review","role":"After decoupling, assess copy coverage, correctness, residual cleanup, and the viability of either promoting or discarding the candidate layout.","counterfactual_removal":"Without the review, an emergency shadow state could become an unexamined permanent configuration."}],"causal_chain":["A flash crowd creates a measurable request gradient toward one key prefix and leaves capacity elsewhere in the cluster.","The controller admits only a bounded sample of that directional flow into a shadow-split channel.","Admitted reads identify currently demanded records, lazily populate their candidate destinations, and test candidate routing against authoritative results.","This converts part of the temporary request concentration into construction and validation of a workload-adapted partition.","The dissipation ledger and feedback monitors expose when duplicate work is consuming more headroom or causing more harm than the channel permits.","Damping reduces coupling as risk rises, and the stop rule decouples the channel before retries or queueing become self-amplifying.","A post-gradient review either authorizes promotion of the verified split or discards the shadow state, returning the service to a viable operating configuration."],"baseline":"Protect the overloaded shard with ordinary autoscaling, rate limiting, or load shedding, then plan a scan-based repartition after traffic stabilizes. This preserves a simpler separation between incident response and layout change but lets the live workload signal expire and may require a later cold copy.","nearest_rivals":["Reactive autoscaling, which adds generic capacity but need not produce a prefix-specific durable layout.","Load shedding or admission control, which suppresses the disequilibrium rather than converting it into partition construction.","Offline trace analysis followed by scan-based resharding, which can design a split without coupling additional work to the live surge but operates later on recorded demand.","Unbounded copy-on-read migration, which also uses accesses to populate a destination but lacks an explicit operating window, dissipation ledger, runaway monitor, and forced decoupling rule."],"remaining_contrastive_claim":"The candidate's distinct causal claim is that a pre-existing hot-prefix request gradient can serve simultaneously as the selector and bounded work channel for constructing and verifying a shadow shard split, provided duplicate work is treated as budgeted dissipation and the channel automatically decouples before it amplifies overload. This is not a claim of novelty or superior effect.","authority_safety":{"decision_authority":"The storage service owner sets eligibility and budgets; the on-call site reliability engineer may start or stop a preapproved shadow-only pilot; only the designated change approver may promote a new routing map.","authorized_first_step":"Run a read-only replay of one previously captured, access-controlled hotspot trace against a simulator of the current and candidate shard maps, with no production routing or record mutation.","excluded_actions":["Creating artificial client load to manufacture a gradient","Automatically promoting the candidate routing map","Weakening consistency or authorization checks","Consuming capacity reserved for authoritative client requests","Expanding beyond the named prefix, trace, or budget","Deleting authoritative or shadow data during the evidence step"],"halt_rollback":"For a later live pilot, setting the shadow sampling rate to zero immediately halts coupling; the original routing map and authoritative source records remain unchanged, queued shadow work is discarded, and the isolated shadow namespace is retained for reviewed cleanup."},"negative_tests":{"strongest_counterevidence":"The flash-crowd access pattern is anomalous: a layout optimized from it increases imbalance or resource use when the service returns to its ordinary workload.","problem_falsifier":"The hotspot cannot be localized to eligible keys, sibling capacity is unavailable, feedback arrives too slowly for safe decoupling, or the existing layout already adapts within the incident's resource and latency budgets.","intervention_falsifier":"Under trace replay, bounded hot-flow coupling produces no more useful copy coverage or routing validation than an equal-cost control schedule, or its modeled duplicate-work cost breaches the predefined headroom budget before producing a promotable candidate.","risks":["Duplicate reads intensify the source hotspot.","Retries and shadow work form positive feedback.","A transient workload is encoded into a poor durable partition.","Shadow copies diverge from authoritative records.","Migration traffic harms unrelated tenants.","Sensitive access traces are retained or exposed beyond their approved purpose.","Repeated emergency splitting creates routing churn and cleanup debt.","A biased sample omits cold records required for a safe promotion."]},"next_evidence_step":"Using one access-controlled trace from a single bounded hotspot interval, replay requests through a simulator that compares no migration, equal-cost non-workload-prioritized copying, and the proposed rate-limited shadow split. Record candidate coverage, routing-verification yield, duplicate reads and bytes, simulated queue headroom, and every stop-rule activation. End after that trace and reject a live pilot unless the intervention falsifier is not triggered; this step estimates feasibility only, not production effect size.","prior_art_status":"UNSEARCHED","diversity_from_prior_proposals":"Runtime-isolated one-shot candidate; no other proposals were inspected or used for comparison. Its domain realization is a distributed-storage hot-prefix event coupled to shadow shard construction.","revision_record":{"parent_version":null,"progress_targets_addressed":[],"conceptual_changes":[],"operational_changes":[],"evidence_changes":[],"claim_changes":[]}}