# 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](../README.md). Transaction Science is the steward, not the proprietor: the wire format and the right to fork are public. --- ## §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). --- ## §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. --- ## §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). #### §3.2.1 Advertised and delivered A Mesh request carries two bounds, and until this revision only one of them was held to a standard of honesty. Energy has a provenance model whose coupling MUST be enforced before sealing (§3.3) — the rule that keeps "measured" from meaning "estimated". Fidelity had none: a backend's level is an **advertisement**, read out of the route table *before* the engine runs, and `fidelity_met` was derived from it and never reconciled with what came back. A backend admitted at `F3` that degraded at serve time still sealed `fidelity_met: 1` against an `F3` floor. Fidelity therefore has two figures, and they are different claims: | figure | who says it | when | |---|---|---| | **advertised** — `ServingEngine::fidelity` | the route table | before the work; the basis the router admits on (§4) | | **delivered** — `ServeOutcome.delivered_fidelity` | the backend that served | after the work | The coupling is normative: - Where the backend reports a delivered level, `fidelity_met` **MUST** be derived from it, not from the advertisement. - A backend **MUST NOT** report a delivered level **above** its advertised rating. The router admitted it on the rating; it cannot raise that basis after the fact. An implementation **MUST** refuse such a serve rather than clamp the figure — clamping hides a misconfigured or dishonest engine behind a receipt that looks ordinary. - Where the backend reports nothing, `fidelity_met` rests on the advertisement. This is the older and weaker basis and is retained, because an engine that cannot report what it served is still conformant. A consumer that requires the stronger basis **MUST** check for `fidelity_delivered` rather than reading `fidelity_met` alone. - The receipt **MUST** carry `fidelity_advertised` and `fidelity_delivered` together or carry neither. Their purpose is the comparison; the advertisement alone adds nothing a verifier does not already have from `backend`. Carrying neither is what a receipt sealed before these fields existed means, so such a receipt is unchanged and `mesh/1` stays byte-stable. **What this does not claim.** A delivered figure is the account of the party that did the work. It is better grounded than a table entry written before the work, and it is not an independent assessment of the output — Mesh does not score responses. What the pair buys is that a divergence between promise and delivery is *visible in the receipt* and attributable to a named backend, where before it was invisible. ### §3.3 Energy and provenance Energy is a two-part integer-microjoule record with an honest provenance tag: ``` Energy { measured_uj: Option, 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. > > The fields are `weights_digest` and `precision` (§6.1), both OPTIONAL. A > backend that can address its weights **SHOULD** report both; one that cannot > omits them, and the receipt then binds the model by `recipe` alone — a name, > which an operator can re-point at other weights while every receipt sealed > under it goes on verifying. That is the weaker basis, and the absence of the > fields is how a verifier can tell it apart from the stronger one, rather than > having to assume. --- ## §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. --- ## §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, delivered_fidelity: Option // §3.2.1 } ``` The advertised level is a promise made before the work; `delivered_fidelity` is what the backend says it actually served. An engine that cannot degrade may report its rating; an engine that can — a fallback, a truncation, a timeout that drops to a cheaper path — reports what it served. Omitting it is conformant and means `fidelity_met` rests on the advertisement (§3.2.1). 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. --- ## §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 — `recipe` is a name, read it with the two fields below | | `weights_digest` | hex content address of the weights that answered (OPTIONAL — §3.6; absent means the receipt binds the model by name alone) | | `precision` | the numeric precision the forward pass ran at, as the backend names it — `fp32`, `fp16`, `bf16`, `int8` (OPTIONAL — §3.6; paired with `weights_digest`, since neither reproduces alone) | | `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_advertised` | the level the backend is rated for (uint, OPTIONAL — paired with the next) | | `fidelity_delivered` | the level the backend says it served (uint, OPTIONAL — §3.2.1) | | `fidelity_met` | `0|1` — was the floor met, on the delivered figure where there is one | | `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 | ModelBased | Estimator` | | `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. --- ## §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/`](../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: ```text cargo run -p mesh-conformance --bin gen-vectors -- ../conformance/v1 ``` --- ## §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. --- ## §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](../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](../jouleclaw/): a backend that executes one inference cheaply is one engine behind the mesh. - It **routes across compute** described by [EOC](../eoc/) and isolated by [Sandbox](../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.