diff --git a/docs/FOG_ENVELOPE_CANONICALIZATION.md b/docs/FOG_ENVELOPE_CANONICALIZATION.md
new file mode 100644
index 0000000..0caafc5
--- /dev/null
+++ b/docs/FOG_ENVELOPE_CANONICALIZATION.md
@@ -0,0 +1,100 @@
+# Fog Envelope Canonicalization and Signing Profile (v0)
+
+This document defines the **recommended evidence profile** for FogVault and FogCompute envelopes until the rules are promoted into first-class schema constraints and ADRs.
+
+## Goals
+
+- deterministic hashing across heterogeneous nodes
+- small, auditable signing surface
+- stable content references independent of transport
+- explicit separation between content hashing, envelope hashing, and settlement logic
+
+## Canonicalization profile
+
+### 1. Canonical JSON
+
+For any JSON payload that is hashed or signed, implementations should:
+
+1. serialize with **JCS** (JSON Canonicalization Scheme; RFC 8785)
+2. encode as UTF-8 bytes
+3. hash with **SHA-256**
+
+This yields the canonical `payloadHash`.
+
+### 2. Content hashing
+
+Raw content referenced by `ContentRef` should be hashed over the raw bytes, not over JSON wrappers. The digest form should be:
+
+```text
+sha256:<lowercase-hex>
+```
+
+### 3. Signature algorithm
+
+The default signature algorithm for Fog envelopes and receipts should be:
+
+- **Ed25519** for detached signatures
+
+Recommended signature field encoding:
+
+```text
+ed25519:<base64url-signature>
+```
+
+### 4. Domain separation
+
+To avoid cross-object signature confusion, signers should sign a domain-separated preimage:
+
+```text
+SRCOS-FOG-V1\n
+<object-type>\n
+<object-id>\n
+<payload-hash>
+```
+
+Where:
+- `<object-type>` is `TopicEnvelope` or `UsageReceipt`
+- `<object-id>` is the object URN
+- `<payload-hash>` is the canonical SHA-256 digest string
+
+### 5. Encryption metadata
+
+When envelopes are encrypted, the authenticated additional data (AAD) should bind at least:
+
+- `topicId`
+- `entryId` or `receiptId`
+- `keyEpoch`
+- `payloadType`
+
+Recommended default content cipher for topic payloads:
+
+- **XChaCha20-Poly1305**
+
+## Verification order
+
+### TopicEnvelope
+
+1. resolve and verify `ContentRef` digests if present
+2. canonicalize `payload`
+3. compute `payloadHash`
+4. verify detached signature
+5. only then evaluate topic semantics / policy
+
+### UsageReceipt
+
+1. canonicalize receipt body
+2. compute `receiptHash`
+3. verify detached signature
+4. verify referenced `WorkOrder` / output refs / settlement mapping
+
+## What this does not settle yet
+
+This v0 profile does **not** yet fix:
+
+- key distribution / rotation mechanics
+- threshold or multisignature receipts
+- CBOR/COSE variants
+- transport-layer framing
+- receipt notarization / timestamp authority integration
+
+Those should land in follow-up ADRs and schema revisions.
diff --git a/docs/FOG_LAYER.md b/docs/FOG_LAYER.md
new file mode 100644
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--- /dev/null
+++ b/docs/FOG_LAYER.md
@@ -0,0 +1,29 @@
+# Fog Layer (FogVault + FogCompute)
+
+This document defines the **Fog Layer** contract surface for the SourceOS/SociOS ecosystem.
+
+The fog layer is designed for **heterogeneous, churny, citizen-fog environments** where machines appear and disappear and cannot be treated as durable infrastructure.
+
+## Architecture summary
+
+### FogVault (storage + topic substrate)
+
+- **Local substrate:** nodes expose fast, capacity-managed *local* storage (e.g., LVM-backed PVs via a local CSI driver such as TopoLVM).
+- **Distributed meaning + replication:** durability and convergence are provided *above* local storage via **append-only Merkle-log topics** (Hypercore). "Folders" and indexes are derived views.
+- **Topic contract:** a topic is an append-only channel with explicit replication policy, membership, and key epochs.
+
+### FogCompute (compute substrate)
+
+- Nodes advertise resource offers (CPU/GPU/RAM/IO windows).
+- Requestors submit work orders (image digests + inputs/outputs + verification policy).
+- Workers emit usage receipts (metered via OS primitives) and optional settlement events.
+- Settlement (tokenization / escrow) is a **pluggable layer**; receipts are the core evidence artifact.
+
+## Contract status
+
+The Fog Layer is represented by the schema set in `schemas/`:
+
+- `Topic.json`, `TopicEnvelope.json`, `ReplicationPolicy.json`, `ContentRef.json`
+- `Offer.json`, `WorkOrder.json`, `UsageReceipt.json`, `SettlementEvent.json`
+
+These are **v0 scaffolds** intended to be evolved via ADRs and semver discipline.
diff --git a/examples/content_ref.json b/examples/content_ref.json
new file mode 100644
index 0000000..85a6af2
--- /dev/null
+++ b/examples/content_ref.json
@@ -0,0 +1,9 @@
+{
+  "digest": "sha256:3d62e3b4c5dd6d04e3d1a2c765a809f0f76ad6f870d13dbb4d4ef7f77e4d2d10",
+  "sizeBytes": 1048576,
+  "mediaType": "application/vnd.srcos.fog.block+json",
+  "uris": [
+    "file:///srv/fog/topics/fog-cache-health/blocks/3d/62/e3b4",
+    "hyper://fog-cache-health/blocks/sha256-3d62e3b4c5dd6d04e3d1a2c765a809f0f76ad6f870d13dbb4d4ef7f77e4d2d10"
+  ]
+}
diff --git a/examples/offer.json b/examples/offer.json
new file mode 100644
index 0000000..b56d99e
--- /dev/null
+++ b/examples/offer.json
@@ -0,0 +1,34 @@
+{
+  "id": "urn:srcos:offer:node-17-cpu-gpu-window-a",
+  "type": "Offer",
+  "specVersion": "2.0.0",
+  "provider": {
+    "subjectId": "urn:srcos:subject:fog-worker-node-17",
+    "nodeId": "node-17"
+  },
+  "resources": {
+    "cpuCores": 8,
+    "memoryBytes": 34359738368,
+    "gpu": {
+      "count": 1,
+      "model": "RTX-4090"
+    },
+    "storageBytes": 536870912000,
+    "networkMbps": 1000
+  },
+  "availability": {
+    "timeWindow": "2026-04-16T00:00:00Z/2026-04-16T08:00:00Z",
+    "maxJobSeconds": 21600
+  },
+  "pricing": {
+    "unit": "fog-credits",
+    "cpuSecond": 0.002,
+    "gpuSecond": 0.02,
+    "gbHour": 0.005
+  },
+  "policy": {
+    "allowWorkloadClasses": ["embedding", "indexing", "batch-inference"],
+    "privacyMode": "topic-encrypted-only",
+    "powerCapWatts": 350
+  }
+}
diff --git a/examples/replication_policy.json b/examples/replication_policy.json
new file mode 100644
index 0000000..71a67d4
--- /dev/null
+++ b/examples/replication_policy.json
@@ -0,0 +1,14 @@
+{
+  "replicas": 3,
+  "minAcks": 1,
+  "neighborhoods": ["lan", "household", "region"],
+  "retention": {
+    "hotDays": 14,
+    "coldDays": 90,
+    "maxBytes": 53687091200
+  },
+  "compaction": {
+    "mode": "snapshot",
+    "intervalEntries": 50000
+  }
+}
diff --git a/examples/settlement_event.json b/examples/settlement_event.json
new file mode 100644
index 0000000..b661518
--- /dev/null
+++ b/examples/settlement_event.json
@@ -0,0 +1,12 @@
+{
+  "id": "urn:srcos:settlement:index-qdrant-shard-20260416-01",
+  "type": "SettlementEvent",
+  "specVersion": "2.0.0",
+  "receiptId": "urn:srcos:receipt:usage:index-qdrant-shard-20260416-01",
+  "amount": {
+    "unit": "fog-credits",
+    "value": 12.84
+  },
+  "backend": "internal-ledger",
+  "txRef": "ledger://fog-credits/2026/04/16/txn-000001"
+}
diff --git a/examples/topic.json b/examples/topic.json
new file mode 100644
index 0000000..b5785f0
--- /dev/null
+++ b/examples/topic.json
@@ -0,0 +1,31 @@
+{
+  "id": "urn:srcos:topic:fog-cache-health",
+  "type": "Topic",
+  "specVersion": "2.0.0",
+  "name": "fog.cache.health",
+  "description": "Health/cache topic for edge-local fog state with append-only Merkle-log replication.",
+  "replication": {
+    "replicas": 3,
+    "minAcks": 1,
+    "neighborhoods": ["lan", "region"],
+    "retention": {
+      "hotDays": 7,
+      "coldDays": 30,
+      "maxBytes": 10737418240
+    },
+    "compaction": {
+      "mode": "checkpoint",
+      "intervalEntries": 10000
+    }
+  },
+  "encryption": {
+    "cipherSuite": "xchacha20poly1305",
+    "keyEpoch": 4,
+    "keyRef": "urn:srcos:key:topic:fog-cache-health:epoch:4"
+  },
+  "members": [
+    "urn:srcos:community:fog-workers",
+    "urn:srcos:community:fog-observers"
+  ],
+  "labels": ["fog", "cache", "ephemeral"]
+}
diff --git a/examples/topic_envelope.json b/examples/topic_envelope.json
new file mode 100644
index 0000000..e9e84a8
--- /dev/null
+++ b/examples/topic_envelope.json
@@ -0,0 +1,33 @@
+{
+  "entryId": "urn:srcos:topic-entry:fog-cache-health:000001",
+  "topicId": "urn:srcos:topic:fog-cache-health",
+  "specVersion": "2.0.0",
+  "occurredAt": "2026-04-16T02:15:00Z",
+  "author": {
+    "subjectId": "urn:srcos:subject:fog-worker-node-17",
+    "nodeId": "node-17"
+  },
+  "payloadType": "PutBlob",
+  "payload": {
+    "path": "/cache/health/worker-17.json",
+    "contentRef": {
+      "digest": "sha256:3d62e3b4c5dd6d04e3d1a2c765a809f0f76ad6f870d13dbb4d4ef7f77e4d2d10",
+      "sizeBytes": 1048576,
+      "mediaType": "application/json"
+    }
+  },
+  "integrity": {
+    "content": {
+      "digest": "sha256:3d62e3b4c5dd6d04e3d1a2c765a809f0f76ad6f870d13dbb4d4ef7f77e4d2d10",
+      "sizeBytes": 1048576,
+      "mediaType": "application/json"
+    },
+    "payloadHash": "sha256:9cd8d6d35b07be7db0d8904b5bd808c95bd1ef674353abce6ebf58c480644e12",
+    "signature": "ed25519:example-signature-topic-entry"
+  },
+  "encryption": {
+    "cipherSuite": "xchacha20poly1305",
+    "keyEpoch": 4,
+    "aad": "topic=fog.cache.health"
+  }
+}
diff --git a/examples/usage_receipt.json b/examples/usage_receipt.json
new file mode 100644
index 0000000..7b2d97b
--- /dev/null
+++ b/examples/usage_receipt.json
@@ -0,0 +1,34 @@
+{
+  "id": "urn:srcos:receipt:usage:index-qdrant-shard-20260416-01",
+  "type": "UsageReceipt",
+  "specVersion": "2.0.0",
+  "workOrderId": "urn:srcos:workorder:index-qdrant-shard-20260416-01",
+  "provider": {
+    "subjectId": "urn:srcos:subject:fog-worker-node-17",
+    "nodeId": "node-17"
+  },
+  "startedAt": "2026-04-16T02:20:00Z",
+  "endedAt": "2026-04-16T02:28:42Z",
+  "exit": {
+    "code": 0,
+    "status": "completed"
+  },
+  "usage": {
+    "cpuSeconds": 3812.41,
+    "memoryPeakBytes": 8912896000,
+    "ioReadBytes": 721420288,
+    "ioWriteBytes": 361758720,
+    "gpuSeconds": 0
+  },
+  "outputs": [
+    {
+      "digest": "sha256:2222222222222222222222222222222222222222222222222222222222222222",
+      "mediaType": "application/vnd.qdrant.snapshot",
+      "sizeBytes": 285212672
+    }
+  ],
+  "integrity": {
+    "receiptHash": "sha256:3333333333333333333333333333333333333333333333333333333333333333",
+    "signature": "ed25519:example-signature-usage-receipt"
+  }
+}
diff --git a/examples/workorder.json b/examples/workorder.json
new file mode 100644
index 0000000..58af860
--- /dev/null
+++ b/examples/workorder.json
@@ -0,0 +1,37 @@
+{
+  "id": "urn:srcos:workorder:index-qdrant-shard-20260416-01",
+  "type": "WorkOrder",
+  "specVersion": "2.0.0",
+  "requestor": {
+    "subjectId": "urn:srcos:subject:mesh-broker-1"
+  },
+  "workload": {
+    "image": "ghcr.io/socioprophet/fog-indexer@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "command": ["/app/index", "--topic", "fog.cache.health", "--shard", "17"],
+    "env": {
+      "QDRANT_URL": "http://qdrant.service.local:6333",
+      "TOPIC_ID": "urn:srcos:topic:fog-cache-health"
+    }
+  },
+  "inputs": [
+    {
+      "digest": "sha256:1111111111111111111111111111111111111111111111111111111111111111",
+      "sizeBytes": 52428800,
+      "mediaType": "application/x-ndjson"
+    }
+  ],
+  "outputs": [
+    {
+      "digest": "sha256:2222222222222222222222222222222222222222222222222222222222222222",
+      "mediaType": "application/vnd.qdrant.snapshot"
+    }
+  ],
+  "verification": {
+    "mode": "replicate",
+    "replicas": 2
+  },
+  "placement": {
+    "requireGpu": false,
+    "neighborhood": "lan"
+  }
+}
diff --git a/schemas/ContentRef.json b/schemas/ContentRef.json
new file mode 100644
index 0000000..768c4f7
--- /dev/null
+++ b/schemas/ContentRef.json
@@ -0,0 +1,34 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/ContentRef.json",
+  "title": "ContentRef",
+  "description": "A content-addressed reference to bytes (blob/chunk/manifest) used by Fog topics and work orders.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["digest"],
+  "properties": {
+    "digest": {
+      "type": "string",
+      "description": "Digest string (recommended form: <algo>:<hex> e.g. sha256:...)."
+    },
+    "sizeBytes": {
+      "type": "integer",
+      "minimum": 0,
+      "description": "Optional size hint in bytes."
+    },
+    "mediaType": {
+      "type": ["string", "null"],
+      "description": "Optional IANA media type hint."
+    },
+    "uris": {
+      "type": "array",
+      "items": {"type": "string"},
+      "description": "Optional locator hints (e.g. file://, s3://, ipfs://, hyper://, https://)."
+    },
+    "chunks": {
+      "type": "array",
+      "items": {"$ref": "ContentRef.json"},
+      "description": "Optional chunk list when the content is a manifest-of-chunks."
+    }
+  }
+}
diff --git a/schemas/Offer.json b/schemas/Offer.json
new file mode 100644
index 0000000..897e9c4
--- /dev/null
+++ b/schemas/Offer.json
@@ -0,0 +1,76 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/Offer.json",
+  "title": "Offer",
+  "description": "FogCompute resource offer published by a provider node/workstation.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["id", "type", "specVersion", "provider", "resources"],
+  "properties": {
+    "id": {
+      "type": "string",
+      "pattern": "^urn:srcos:offer:",
+      "description": "Stable URN identifier. Pattern: urn:srcos:offer:<local-id>"
+    },
+    "type": {
+      "const": "Offer",
+      "description": "Discriminator constant — always \"Offer\"."
+    },
+    "specVersion": {
+      "type": "string",
+      "description": "Spec version of this document, e.g. \"2.0.0\"."
+    },
+    "provider": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["subjectId"],
+      "properties": {
+        "subjectId": {"type": "string", "description": "Provider subject URN."},
+        "nodeId": {"type": ["string", "null"], "description": "Optional provider node identifier."}
+      }
+    },
+    "resources": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "cpuCores": {"type": "number", "minimum": 0},
+        "memoryBytes": {"type": "integer", "minimum": 0},
+        "gpu": {
+          "type": "object",
+          "additionalProperties": false,
+          "properties": {
+            "count": {"type": "integer", "minimum": 0},
+            "model": {"type": ["string", "null"]}
+          }
+        },
+        "storageBytes": {"type": "integer", "minimum": 0},
+        "networkMbps": {"type": "number", "minimum": 0}
+      },
+      "description": "Advertised resource caps."
+    },
+    "availability": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "timeWindow": {"type": ["string", "null"], "description": "Optional ISO-8601 interval window."},
+        "maxJobSeconds": {"type": ["integer", "null"], "minimum": 0}
+      }
+    },
+    "pricing": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "unit": {"type": ["string", "null"], "description": "e.g. credits, token, usd."},
+        "cpuSecond": {"type": ["number", "null"], "minimum": 0},
+        "gpuSecond": {"type": ["number", "null"], "minimum": 0},
+        "gbHour": {"type": ["number", "null"], "minimum": 0}
+      },
+      "description": "Optional pricing schedule."
+    },
+    "policy": {
+      "type": "object",
+      "additionalProperties": true,
+      "description": "Optional provider constraints (allow/deny workload classes, privacy mode, power caps)."
+    }
+  }
+}
diff --git a/schemas/ReplicationPolicy.json b/schemas/ReplicationPolicy.json
new file mode 100644
index 0000000..b348fdf
--- /dev/null
+++ b/schemas/ReplicationPolicy.json
@@ -0,0 +1,45 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/ReplicationPolicy.json",
+  "title": "ReplicationPolicy",
+  "description": "Replication and retention policy for a Fog topic. This is a v0 scaffold; fields will evolve via ADRs.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["replicas"],
+  "properties": {
+    "replicas": {
+      "type": "integer",
+      "minimum": 1,
+      "description": "Target replica count across distinct peers/neighborhoods."
+    },
+    "minAcks": {
+      "type": "integer",
+      "minimum": 0,
+      "description": "Minimum acknowledgements required for a write to be considered accepted (0 = fire-and-forget)."
+    },
+    "neighborhoods": {
+      "type": "array",
+      "items": {"type": "string"},
+      "description": "Optional locality buckets (e.g. lan, household, region, friend-mesh) used for placement diversity."
+    },
+    "retention": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "hotDays": {"type": "integer", "minimum": 0},
+        "coldDays": {"type": "integer", "minimum": 0},
+        "maxBytes": {"type": "integer", "minimum": 0}
+      },
+      "description": "Retention hints for hot/cold storage and maximum topic size."
+    },
+    "compaction": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "mode": {"enum": ["none", "checkpoint", "snapshot"]},
+        "intervalEntries": {"type": "integer", "minimum": 0}
+      },
+      "description": "Compaction/checkpoint strategy for append-only growth."
+    }
+  }
+}
diff --git a/schemas/SettlementEvent.json b/schemas/SettlementEvent.json
new file mode 100644
index 0000000..3822c7e
--- /dev/null
+++ b/schemas/SettlementEvent.json
@@ -0,0 +1,46 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/SettlementEvent.json",
+  "title": "SettlementEvent",
+  "description": "Optional settlement event mapping a UsageReceipt to credits/tokens/escrow outcomes. Pluggable layer.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["id", "type", "specVersion", "receiptId"],
+  "properties": {
+    "id": {
+      "type": "string",
+      "pattern": "^urn:srcos:settlement:",
+      "description": "Stable URN identifier. Pattern: urn:srcos:settlement:<local-id>"
+    },
+    "type": {
+      "const": "SettlementEvent",
+      "description": "Discriminator constant — always \"SettlementEvent\"."
+    },
+    "specVersion": {
+      "type": "string",
+      "description": "Spec version of this document, e.g. \"2.0.0\"."
+    },
+    "receiptId": {
+      "type": "string",
+      "pattern": "^urn:srcos:receipt:usage:",
+      "description": "UsageReceipt URN."
+    },
+    "amount": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "unit": {"type": "string"},
+        "value": {"type": "number"}
+      },
+      "description": "Settled amount (credits/tokens)."
+    },
+    "backend": {
+      "type": ["string", "null"],
+      "description": "Settlement backend identifier (e.g., internal-ledger, iexec, akash, golem)."
+    },
+    "txRef": {
+      "type": ["string", "null"],
+      "description": "Optional settlement transaction reference."
+    }
+  }
+}
diff --git a/schemas/Topic.json b/schemas/Topic.json
new file mode 100644
index 0000000..445dd34
--- /dev/null
+++ b/schemas/Topic.json
@@ -0,0 +1,55 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/Topic.json",
+  "title": "Topic",
+  "description": "A FogVault topic: an append-only Merkle-log channel with explicit replication policy, membership, and key epochs.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["id", "type", "specVersion", "name", "replication"],
+  "properties": {
+    "id": {
+      "type": "string",
+      "pattern": "^urn:srcos:topic:",
+      "description": "Stable URN identifier. Pattern: urn:srcos:topic:<local-id>"
+    },
+    "type": {
+      "const": "Topic",
+      "description": "Discriminator constant — always \"Topic\"."
+    },
+    "specVersion": {
+      "type": "string",
+      "description": "Spec version of this document, e.g. \"2.0.0\"."
+    },
+    "name": {
+      "type": "string",
+      "description": "Human-readable topic name (stable label)."
+    },
+    "description": {
+      "type": ["string", "null"],
+      "description": "Optional free-text description."
+    },
+    "replication": {
+      "$ref": "ReplicationPolicy.json"
+    },
+    "encryption": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "cipherSuite": {"type": "string"},
+        "keyEpoch": {"type": "integer", "minimum": 0},
+        "keyRef": {"type": ["string", "null"], "description": "Opaque reference to key material (never raw keys)."}
+      },
+      "description": "Topic encryption metadata (epoch-based rotation)."
+    },
+    "members": {
+      "type": "array",
+      "items": {"type": "string"},
+      "description": "Optional member identities (subject URNs) authorized for this topic."
+    },
+    "labels": {
+      "type": "array",
+      "items": {"type": "string"},
+      "description": "Optional tags/labels for discovery and policy."
+    }
+  }
+}
diff --git a/schemas/TopicEnvelope.json b/schemas/TopicEnvelope.json
new file mode 100644
index 0000000..6d6cadb
--- /dev/null
+++ b/schemas/TopicEnvelope.json
@@ -0,0 +1,74 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/TopicEnvelope.json",
+  "title": "TopicEnvelope",
+  "description": "A FogVault append-only topic entry envelope. This is intentionally generic; concrete payload typing is expressed via specVersion + payloadType.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["entryId", "topicId", "specVersion", "occurredAt", "payloadType", "payload"],
+  "properties": {
+    "entryId": {
+      "type": "string",
+      "pattern": "^urn:srcos:topic-entry:",
+      "description": "Stable URN identifier for this entry. Pattern: urn:srcos:topic-entry:<local-id>"
+    },
+    "topicId": {
+      "type": "string",
+      "pattern": "^urn:srcos:topic:",
+      "description": "Topic URN."
+    },
+    "specVersion": {
+      "type": "string",
+      "description": "Spec version of this document, e.g. \"2.0.0\"."
+    },
+    "occurredAt": {
+      "type": "string",
+      "format": "date-time",
+      "description": "ISO 8601 date-time when this entry was produced."
+    },
+    "author": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "subjectId": {"type": "string"},
+        "nodeId": {"type": ["string", "null"]}
+      },
+      "description": "Producer identity (subject and optional node)."
+    },
+    "payloadType": {
+      "type": "string",
+      "description": "Typed discriminator for the payload (e.g. PutBlob, Link, IndexHint, OfferUpserted)."
+    },
+    "payload": {
+      "type": "object",
+      "additionalProperties": true,
+      "description": "Payload object typed by payloadType."
+    },
+    "integrity": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "content": {"$ref": "ContentRef.json"},
+        "payloadHash": {
+          "type": ["string", "null"],
+          "description": "Optional hash of canonical payload bytes."
+        },
+        "signature": {
+          "type": ["string", "null"],
+          "description": "Optional signature over payloadHash."
+        }
+      },
+      "description": "Optional integrity envelope (hash and signature)."
+    },
+    "encryption": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "cipherSuite": {"type": ["string", "null"]},
+        "keyEpoch": {"type": ["integer", "null"], "minimum": 0},
+        "aad": {"type": ["string", "null"], "description": "Optional external AAD binding (encoded)."}
+      },
+      "description": "Optional encryption metadata for encrypted payloads."
+    }
+  }
+}
diff --git a/schemas/UsageReceipt.json b/schemas/UsageReceipt.json
new file mode 100644
index 0000000..ff0922f
--- /dev/null
+++ b/schemas/UsageReceipt.json
@@ -0,0 +1,74 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/UsageReceipt.json",
+  "title": "UsageReceipt",
+  "description": "FogCompute usage receipt emitted by a worker for a completed work order.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["id", "type", "specVersion", "workOrderId", "provider", "startedAt", "endedAt", "usage"],
+  "properties": {
+    "id": {
+      "type": "string",
+      "pattern": "^urn:srcos:receipt:usage:",
+      "description": "Stable URN identifier. Pattern: urn:srcos:receipt:usage:<local-id>"
+    },
+    "type": {
+      "const": "UsageReceipt",
+      "description": "Discriminator constant — always \"UsageReceipt\"."
+    },
+    "specVersion": {
+      "type": "string",
+      "description": "Spec version of this document, e.g. \"2.0.0\"."
+    },
+    "workOrderId": {
+      "type": "string",
+      "pattern": "^urn:srcos:workorder:",
+      "description": "Associated WorkOrder URN."
+    },
+    "provider": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["subjectId"],
+      "properties": {
+        "subjectId": {"type": "string"},
+        "nodeId": {"type": ["string", "null"]}
+      }
+    },
+    "startedAt": {"type": "string", "format": "date-time"},
+    "endedAt": {"type": "string", "format": "date-time"},
+    "exit": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "code": {"type": ["integer", "null"]},
+        "status": {"type": ["string", "null"]}
+      }
+    },
+    "usage": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "cpuSeconds": {"type": "number", "minimum": 0},
+        "memoryPeakBytes": {"type": "integer", "minimum": 0},
+        "ioReadBytes": {"type": "integer", "minimum": 0},
+        "ioWriteBytes": {"type": "integer", "minimum": 0},
+        "gpuSeconds": {"type": "number", "minimum": 0}
+      },
+      "description": "Metered usage (best-effort, OS-derived)."
+    },
+    "outputs": {
+      "type": "array",
+      "items": {"$ref": "ContentRef.json"},
+      "description": "Output content references produced by the work order."
+    },
+    "integrity": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "receiptHash": {"type": ["string", "null"]},
+        "signature": {"type": ["string", "null"]}
+      },
+      "description": "Optional receipt hash and signature."
+    }
+  }
+}
diff --git a/schemas/WorkOrder.json b/schemas/WorkOrder.json
new file mode 100644
index 0000000..7f9431b
--- /dev/null
+++ b/schemas/WorkOrder.json
@@ -0,0 +1,82 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/WorkOrder.json",
+  "title": "WorkOrder",
+  "description": "FogCompute work order: container/image digest + inputs/outputs + verification policy.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["id", "type", "specVersion", "requestor", "workload"],
+  "properties": {
+    "id": {
+      "type": "string",
+      "pattern": "^urn:srcos:workorder:",
+      "description": "Stable URN identifier. Pattern: urn:srcos:workorder:<local-id>"
+    },
+    "type": {
+      "const": "WorkOrder",
+      "description": "Discriminator constant — always \"WorkOrder\"."
+    },
+    "specVersion": {
+      "type": "string",
+      "description": "Spec version of this document, e.g. \"2.0.0\"."
+    },
+    "requestor": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["subjectId"],
+      "properties": {
+        "subjectId": {"type": "string"}
+      },
+      "description": "Requestor identity."
+    },
+    "workload": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["image"],
+      "properties": {
+        "image": {
+          "type": "string",
+          "description": "Container image reference (recommended: digest-pinned)."
+        },
+        "command": {
+          "type": ["array", "null"],
+          "items": {"type": "string"},
+          "description": "Optional argv-style command override."
+        },
+        "env": {
+          "type": "object",
+          "additionalProperties": {"type": "string"},
+          "description": "Optional environment variables."
+        }
+      }
+    },
+    "inputs": {
+      "type": "array",
+      "items": {"$ref": "ContentRef.json"},
+      "description": "Input content references."
+    },
+    "outputs": {
+      "type": "array",
+      "items": {"$ref": "ContentRef.json"},
+      "description": "Optional expected output refs (or output policy manifests)."
+    },
+    "verification": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "mode": {"enum": ["none", "tee", "replicate", "spotcheck", "reputation"]},
+        "replicas": {"type": ["integer", "null"], "minimum": 0}
+      },
+      "description": "Verification policy (TEE or replication-based)."
+    },
+    "placement": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "requireGpu": {"type": "boolean"},
+        "neighborhood": {"type": ["string", "null"]}
+      },
+      "description": "Optional placement constraints."
+    }
+  }
+}