atlas-verify-incoming

name	atlas-verify-incoming
description	Receiver-side ECL integrity gate (blocking, symmetric). Refuses to process any upstream artefact whose sibling .envelope.json lacks a verify_pass trace event from the orchestrator. Use when reading any upstream artefact handed off to ATLAS that carries a sibling .envelope.json. Symmetric across all Eidolons — every Eidolon enforces it identically per ECL §6.2.2.
metadata	{"methodology":"ATLAS","phase":"cross-cutting"}

Verify-Incoming Skill — ATLAS (blocking, symmetric)

When to use

Load this skill when reading any upstream artefact at path P where a sibling file ${P%.*}.envelope.json exists in the same directory. If no .envelope.json sibling exists, skip the gate silently and process normally.

---

Receiver-side integrity gate for inbound ECL hand-offs, converged on the ECL v2.0 blocking gate shape (canonical reference: Kupo's skills/verify-incoming.md). When an upstream artefact arrives with a sibling .envelope.json, ATLAS MUST NOT process the payload unless its SHA-256 integrity has been verified and passed. This is the blocking posture mandated by ECL v2.0 §6.2.2 ("a receiver SHALL NOT process a payload whose integrity tag does not match"). It is symmetric: every Eidolon in the roster ships this same gate, so no hand-off edge can silently skip it.

Posture change (vs. earlier opt-in warn-only): previous versions logged a warning and processed the payload anyway. That is now superseded. On an unverified or failed envelope this skill refuses and hands back to the orchestrator. Provenance is only a differentiator if receivers actually reject tampered payloads — end to end, not just at the orchestrator.

---

Where the cryptographic check runs (and why the receiver only reads)

ATLAS's tool surface cannot run the SHA-256 gate itself (receiver Eidolons have restricted or no Bash). The mechanical check therefore runs at the orchestrator, once, before ATLAS is dispatched:

# Orchestrator pre-step (host LLM, full Bash) — already shipped in the nexus CLI:
eidolons verify-envelope <artefact>.envelope.json --block      # exit 3 ⇒ tamper/mismatch
#   …or, when routing through the kernel:
eidolons run --verify <artefact>.envelope.json --verify-block  # gates the route

The gate writes a verify_pass (or verify_fail) trace event keyed by message_id. ATLAS then enforces the result using only Read — no Bash required:

1. Read .eidolons/.trace/<thread_id>.jsonl (the thread_id is envelope.thread_id).
2. Find the event whose message_id matches envelope.message_id.
3. verify_pass with integrity_method: "sha256" → integrity confirmed, proceed to contract conformance below.
4. verify_fail, or no matching event → integrity unconfirmed → REFUSE (see Failure Mode). Do not process the payload.

Defense-in-depth (optional): if ATLAS's host happens to grant Bash with eidolons on PATH, it MAY independently re-run eidolons verify-envelope <env> --block and abort on a non-zero exit. The orchestrator pre-verify is the contract; self-verification is an additional guard, never a replacement.

---

Memory: Recall + Ingest (CRYSTALIUM)

On an inbound hand-off, first recall related prior context (if CRYSTALIUM available):

mcp__crystalium__recall(
  scope  = { project: <cwd-project>, agent_class_visibility: "atlas" },
  query  = <artefact GOAL + from.eidolon + artifact.kind>,
  k      = 5,
  layers = ["semantic", "episodic", "procedural"]
)

Only after the integrity gate passes (verify_pass) ingest the received envelope to record the inbound edge:

mcp__crystalium__ingest(
  envelope = <received .envelope.json contents>,
  payload  = <artefact payload contents>
)

Never ingest an envelope that failed or skipped verification. Graceful skip: if mcp__crystalium__* tools are unavailable, skip both calls silently.

---

Trigger

Load this skill automatically when:

• Reading an upstream artefact at path P, and
• A sibling file ${P%.*}.envelope.json exists in the same directory.

Detection rule (POSIX sh compatible):

envelope_path="${artefact_path%.*}.envelope.json"
[ -f "$envelope_path" ] && load_skill "verify-incoming"

If no .envelope.json sibling exists, this is a non-ECL artefact — skip the gate silently and process normally.

---

Inbound edges ATLAS accepts

to.eidolon MUST equal atlas. from.eidolon MUST be a declared upstream sender. Performative and artifact.kind are validated against the ECL inbound contract contracts/<from>-to-atlas.yaml (source of truth); the table below is the convenience summary:

from	performative(s)	artifact.kind
vigil	PROPOSE, CRITIQUE, INFORM	root-cause-report
forge	PROPOSE, INFORM, CRITIQUE	reasoning-report

A hand-off whose from.eidolon is not listed, or whose performative / artifact.kind is not allowed for that edge, is an UNDECLARED_EDGE / PERFORMATIVE_NOT_ALLOWED / ARTIFACT_KIND_NOT_ALLOWED violation → REFUSE.

---

Failure Mode (BLOCKING — refuse, do not process)

On any integrity or contract failure:

1. Append a verify_fail event to .eidolons/.trace/<thread_id>.jsonl.
2. Print to stderr: [atlas-verify-incoming] REFUSE: <FAILURE_CODE> from <from.eidolon>.
3. Do not process the payload. Hand control back to the orchestrator with a refusal. The orchestrator routes the failure to VIGIL (integrity / tamper investigation) or to the human — never a silent retry, never a silent process-anyway.

Failure codes: INTEGRITY_MISMATCH, UNVERIFIED (no verify_pass on record), SCHEMA_INVALID, UNDECLARED_EDGE, PERFORMATIVE_NOT_ALLOWED, ARTIFACT_KIND_NOT_ALLOWED, CONTEXT_OVER_BUDGET, MISSING_REQUIRED_SECTION (full ECL v2.0 §5.3 set).

On success: append verify_pass, then proceed with the payload.

---

Trace Events

Append one JSONL line per verification to .eidolons/.trace/<thread_id>.jsonl (create if absent). The thread_id comes from envelope.thread_id; if the envelope is unparseable, use unknown.

verify_pass:

{"ts":"<RFC3339>","event":"verify_pass","message_id":"<uuid>","thread_id":"<uuid>","from":"<eidolon>@<version>","to":"atlas@<version>","performative":"<performative>","integrity_method":"sha256"}

verify_fail:

{"ts":"<RFC3339>","event":"verify_fail","message_id":"<uuid>","thread_id":"<uuid>","from":"<eidolon>@<version>","to":"atlas@<version>","integrity_method":"sha256","verify_failure_code":"<CODE>","decision":"refused"}

---

Notes

• Blocking, not warn-only. Refusal is the whole point: a receiver that processes a tamper-flagged payload defeats the provenance guarantee.
• Symmetric. All six Eidolons ship this gate with identical semantics; the only per-Eidolon variation is the inbound-edge table above.
• Mechanical gate, single source of truth. The SHA-256 comparison is the nexus eidolons verify-envelope verb (ECL v2.0 §6.2.2) — never re-implemented or LLM-estimated in this skill.
• Read-only enforcement. The receiver needs only Read to consult the trace; this is why the gate is symmetric across tool-less Eidolons.

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Verify-Incoming Skill — blocking, symmetric, mechanical-gate-backed (ECL v2.0 §6.2.2)