open-standards/mesh/SPEC.md

Mesh — Energy-Accounted Inference Serving & Routing

Version: 0.1.0-draft.1 · Status: Draft · Profile: mesh/1 Specification text: CC-BY-4.0 · Reference code (mesh-rs/): Apache-2.0

Mesh is the open standard for serving and routing inference as a metered transaction. A request declares a joule ceiling and a fidelity floor; the mesh routes it to the cheapest-sufficient model on the cheapest-sufficient backend, serves it under an energy meter, and seals a receipt whose headline figure is microjoules per accepted output token — measured at the meter, not estimated from a price list.

Mesh is one of the Transaction Science open standards. Transaction Science is the steward, not the proprietor: the wire format and the right to fork are public.

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§1 Why Mesh exists

The serving shelf reports two numbers: dollars per token and tokens per second. Neither tells an operator, an auditor, or a regulator what an inference cost — in the one unit that is physical, comparable across hardware, and impossible to inflate: the joule. Mesh makes that number first-class. Every served inference produces a signed receipt carrying the route that was taken and why, the recipe that served it, the honest provenance of the energy figure, and the joules per accepted token.

Mesh does not replace the runtime that executes one inference, nor the substrate that supplies the compute. It is the front door in front of many models and many backends: the layer that decides where a request goes, meters what it spent, and proves it (§9).

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§2 Roles and the serve lifecycle

A Mesh deployment has four roles:

• Caller — issues a ServeRequest and, optionally, the JCP grant that authorises it.
• Router — selects a backend (§4).
• Engine — a backend that serves the request (§5).
• Steward — the endpoint that meters the span (§5/§6) and seals the receipt (§6). The steward identity is the COSE kid and signs the receipt log.

One serve proceeds in four phases, in order:

1. Authorise. If the request rides on a JCP SignedGrant, the steward MUST verify the issuer signature, confirm the capability permits the action infer on the request's content id, and confirm the grant's joule budget is ≥ the request's joule ceiling. A failure at any step aborts the serve before any work is done.
2. Route. The router selects the cheapest admissible backend (§4). If none is admissible, the serve fails with the router's recorded reason.
3. Meter. The steward opens an energy window, calls the engine, and closes the window. Energy MUST be metered around the engine; an engine MUST NOT self-report energy.
4. Seal. The steward builds the receipt (§6), stamps it into its hash-chained log, and seals it as a JCR-1 envelope.

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§3 The request and the energy record

§3.1 ServeRequest

A request is content-addressed. Its identity request_id = ContentId.of(request) is the resource a JCP capability authorises and the request_id on the receipt.

Field	Type	Meaning
prompt_hash	ContentId (BLAKE3)	content address of the prompt bytes — never the prompt text
prompt_tokens	u32	declared input token count (for the estimate)
max_tokens	u32	output token ceiling
fidelity_floor	Fidelity	minimum acceptable fidelity (§3.2)
joule_ceiling_uj	u64	hard energy budget, microjoules

A conforming request MUST carry both a fidelity_floor and a joule_ceiling_uj. The pair is the contract: give me an answer at least this good, for at most this much energy.

A request MAY additionally carry a decision (§3.6), which says it is asking for a bounded typed decision rather than generated text. Its absence is a generation, and is omitted from the canonical form — so the request_id of every request written before this field existed is unchanged.

§3.2 Fidelity

Fidelity is an ordered scale F0 … F4 — F0 the coarsest sufficient answer (cache / lawful / tiny model), F4 a frontier-grade response. Ordering is normative: a backend is admissible only when its level ≥ the request's floor (§4).

§3.3 Energy and provenance

Energy is a two-part integer-microjoule record with an honest provenance tag:

Energy { measured_uj: Option<u64>, estimated_uj: u64, provenance: Provenance }
Provenance ∈ { HwShunt, ModelBased, Estimator }

The coupling is normative and MUST be enforced before a receipt is sealed:

• HwShunt ⇒ measured_uj is present (a hardware reading exists).
• Estimator ⇒ measured_uj is absent (no measurement is implied).
• ModelBased ⇒ measured_uj MAY be absent.

A receipt that violates the coupling MUST NOT be sealable. This is the rule that keeps "measured" honest: a deployment with no hardware meter reports Estimator and says so, rather than dressing an estimate up as a measurement.

HwShunt covers a shunt and a vendor energy counter (RAPL, NVML, Apple IOReport), but a counter counts only while it is live:

A reading from a vendor energy counter (RAPL, NVML, Apple IOReport, …) MAY be graded as a hardware reading only while the counter is demonstrably live for the domain the figure claims: the implementation MUST have observed the counter covering that domain advance under load (for Apple IOReport: the CPU energy rail itself advancing in at least 5 sample intervals, in at least 4 of every 5, over at least 300 ms while the probing thread burns CPU). A counter that is present but not live — frozen, or republished in lumps — MUST NOT produce a hardware-graded figure; the implementation falls back to its estimator or reports the work unmetered, and SHOULD record why. A figure MUST NOT claim coverage of a domain its counter does not read; where the format has a coverage field, such a figure is Partial.

mesh/1 has no coverage field. So a figure from a counter that does not cover the whole request, such as a GPU counter on a host whose CPU has none, MUST NOT be graded HwShunt.

§3.6 Typed decisions — the other unit of work

A decision model takes state plus typed questions and returns a calibrated probability per allowed answer, generating no text. The category converged through 2026 on three primitives — a proposition (noul), a choice over 1–255 named options, and a score over an ordered rubric — and backends score the schema non-autoregressively rather than emitting tokens.

Everything else in this spec measures work in tokens, and a decision's output token count is zero. Measured on a 421M decision model: output_tokens: 0, with 132 input tokens of which 121 were the question schema and 11 the state under judgement. Three consequences follow, and a conforming implementation MUST handle each.

A request asking for a decision carries:

Field	Type	Meaning
questions	u32	typed questions in the request
options_scored	u32	options scored across all of them
schema_tokens	u32	how many of prompt_tokens are schema, not state

1. It MUST NOT be priced for tokens it cannot emit. The estimate for a decision MUST exclude max_tokens. Including it refuses work at a ceiling that would in fact have covered it.
2. Cost MUST be allowed to follow the schema. A profile MAY declare a cost per scored option; one question over 20 options is more work than one over 2 at identical token counts, and no token count expresses the difference. Declaring nothing reproduces the token-only model exactly, so an unmeasured profile claims nothing.
3. The efficiency figure MUST be defined. uj_per_accepted_token (§6) is undefined when no tokens were accepted, which is every request in this category. A decision receipt MUST instead carry uj_per_decision, and SHOULD carry uj_per_option_scored. The unit of work is the answered question.

schema_tokens is reported because a fixed schema is a cacheable input prefix — distinct from cache_hit_tokens, which counts output tokens served from cache, of which a decision has none. In the measured request 92% of the input was schema, so a reader that cannot see the split cannot tell a cold decision from a warm one.

Why a decision receipt is worth more than a generation receipt. A decision is a single forward pass with no sampling. Given the weight digest, revision and numeric precision, it is reproducible — so a receipt over one is verifiable by re-execution, which a receipt over sampled text can never be. A receipt for a decision SHOULD therefore bind the weight digest and the precision; the probabilities of a published decision model differ between fp16 and fp32 even where the selected answer agrees, so a receipt that omits precision does not reproduce.

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§4 Routing — cheapest-sufficient

For each registered backend the router computes an estimate est_total_uj = uj_per_token × (prompt_tokens + max_tokens), or for a typed decision (§3.6) uj_per_token × prompt_tokens + uj_per_option_scored × options_scored, and marks it admissible iff:

backend.fidelity ≥ request.fidelity_floor   AND   est_total_uj ≤ request.joule_ceiling_uj

The router MUST choose the admissible backend with the lowest est_total_uj. Ties are broken deterministically (registration order). When no backend is admissible the serve fails, and the decision records why.

The router MUST record, for every backend it weighed, a RouteCandidate with its fidelity, estimate, admissibility, and — when inadmissible — a human-readable reason (below floor / over ceiling). The chosen route MUST carry a one-line justification. This is what makes a route auditable from the receipt alone: the cheapest sufficient answer is preferred and a frontier model is the expensive last resort, and the comparison is denominated in joules.

A model is addressed as a recipe — a base plus optional merges/adapters — not a fixed blob, so the receipt can record which composed model answered.

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§5 The serving engine

A backend implements one interface: advertise a fidelity level and a modeled per-token energy cost, and serve a request producing tokens and a ServeOutcome:

ServeOutcome {
  tokens_in, tokens_out, tokens_accepted,
  cache_hit_tokens, spec_proposed, spec_accepted
}

The input token payload travels with the serve call, alongside the request — it is never part of the request's sealed identity and never enters the receipt, which records only the content-addressed prompt_hash (§3.1). A receipt is therefore safe to publish without disclosing the prompt.

tokens_accepted is the denominator of the wedge metric. For greedy decode it equals tokens_out; under speculative decoding it is the number of proposed tokens the target model accepted. cache_hit_tokens records output served from a prefix/result cache (energy saved). An engine MUST do real work proportional to the tokens it serves so the surrounding meter reads a real span; it MUST NOT self-report energy.

The reference engine (mesh-engine::ReferenceEngine) is deterministic and weights-free, for conformance. Production backends — a quantized device-resident decoder, a high-throughput batching server — implement the same interface and drop in unchanged; mesh-engine-gguf::GgufEngine (behind the gguf feature) is one such backend over a pure-Rust GGUF/Metal decoder, so the mesh routes and meters real model tokens.

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§6 The receipt — mesh/1

A MeshReceipt is sealed with JCR-1: canonical det-CBOR (RFC 8949 §4.2.1) inside a COSE_Sign1 envelope (RFC 9052, EdDSA/Ed25519, alg = -8), byte-compatible with the rest of the family's receipts. The signed core forbids floats, booleans, and nulls; booleans are encoded as 0|1 uints and absent options dropped.

§6.1 Wire fields (mesh/1)

Key	Meaning
mesh_receipt	"mesh/1"
request_id	hex content id of the request
grant_id	hex JCP grant id this inference debited (omitted if ungranted)
backend, recipe	the backend and composed model that served it
route	the router's one-line justification
tokens_in/out/accepted, cache_hit_tokens, spec_proposed/accepted	the outcome counters
fidelity_floor	the floor the request demanded (uint)
fidelity_met	`0
estimated_uj	always present
measured_uj	present iff provenance is HwShunt
uj_per_accepted_token	the wedge metric for a generation — energy.uj() / tokens_accepted; omitted when no tokens were accepted
questions_answered, options_scored, schema_tokens	present iff the request was a typed decision (§3.6)
uj_per_decision	the wedge metric for a decision — energy.uj() / questions_answered
uj_per_option_scored	the finer decision figure — energy.uj() / options_scored
energy_provenance	`HwShunt
sequence, prev	hash-chain position and prior envelope's content id
nonce, steward	per-receipt nonce and the sealing identity (COSE kid)

§6.2 The wedge metric

uj_per_accepted_token = energy.uj() / tokens_accepted, where energy.uj() is the measured figure if present, else the estimate. It is null/absent when no tokens were accepted. This is the number Mesh exists to make legible, and it is sealed into every receipt.

§6.3 Hash chain

A steward keeps a receipt log. Appending a receipt stamps its sequence (from 0) and prev (the content id of the previous sealed envelope; absent at genesis), seals it, and advances the head. The log is tamper-evident end to end: altering any envelope breaks verification of that receipt and the chain link from the next.

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§7 Conformance

A conforming implementation MUST:

1. Reject a serve whose grant fails verification, does not permit infer on the request, or carries a budget below the request's joule ceiling (§2.1).
2. Choose the cheapest admissible backend and record every candidate weighed (§4).
3. Meter energy around the engine and tag provenance honestly, enforcing the Energy coupling before sealing (§3.3).
4. Seal the receipt as a JCR-1 mesh/1 envelope and compute uj_per_accepted_token (§6).
5. Maintain a tamper-evident hash chain (§6.3).

The published vectors in ../conformance/v1/ pin a deterministic reference serve. reference/signed_core.hex MUST canonical-CBOR encode identically across implementations, and reference/envelope.hex MUST be reproducible from it with the steward key in meta.json. Regenerate with:

cargo run -p mesh-conformance --bin gen-vectors -- ../conformance/v1

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§8 Security considerations

Mesh composes proven primitives: Ed25519 signatures, BLAKE3 content addressing, RFC 9052 COSE_Sign1, and the JCP capability model. It introduces no new cryptography. Two properties are correctness, not style:

• Authorisation happens outside the model. The grant check (§2.1) is enforced by the steward before any inference runs; a prompt cannot grant itself budget or capability.
• Honesty is enforced at seal time. A receipt cannot claim a measurement it does not have (§3.3). An operator without a hardware meter produces honest Estimator receipts.

Energy figures are only as honest as the worst meter in the span. A receipt's provenance tag states which meter produced its figure; consumers SHOULD treat Estimator figures as bounds, not measurements.

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§9 Relationship to the family

Mesh is the serving + routing fabric. It is expressed in primitives the family already publishes, and it composes with the neighbouring standards rather than duplicating them:

• It rides on JCP: a serve request is authorised by a JCP Grant (capability ⊗ joule-budget), and the receipt seals in JCR-1 — the same envelope every family receipt uses.
• It dispatches to runtimes such as JouleClaw: a backend that executes one inference cheaply is one engine behind the mesh.
• It routes across compute described by EOC and isolated by Sandbox: a backend may be a metered, attested execution target.

The boundary is deliberate: a runtime executes one inference; Mesh routes across many models and many backends and proves what each one cost.