diff --git a/schemas/README.md b/schemas/README.md
new file mode 100644
index 0000000..db94d6e
--- /dev/null
+++ b/schemas/README.md
@@ -0,0 +1,277 @@
+# Proposed durable agent state 2.0 contract
+
+**Proposal for joint Python, .NET, and Durable Task review; not runtime activation.**
+This change contains only a JSON Schema, synthetic fixtures, and documentation.
+Neither Python nor .NET is authorized to emit `2.0.0` by this proposal or by a
+successful schema validation. Merge of this contract proposal requires agreement
+on compatible-reader/consumer semantics and the rollout floor; emitting 2.0
+requires a separately reviewed implementation and an enforced deployment gate.
+
+The motivation is to separate execution/delivery completion from conversation
+history that may be compacted or evicted. Preserving unknown JSON alone cannot
+prevent duplicate execution if a reader still uses transcript responses to
+decide whether a request completed. [ADR discussion #88](https://github.com/microsoft/agent-framework-durable-extension/pull/88)
+provides related compaction/retention context, not a mandate for this exact schema.
+
+## Version and reader policy
+
+The [Draft 2020-12 schema](durable-agent-entity-state.json) describes exact review
+snapshots `1.0.0`, `1.1.0`, proposed `1.2.0`, and proposed `2.0.0`; it is not a
+list of versions supported by today's runtimes. The proposed 1.2 fields are
+included for compatibility discussion, not claimed as released Python output.
+Legacy transcript entries retain the existing permissive entry shape. The
+three mailbox/binding fields are forbidden in 1.x, even if empty. Version 2.0
+requires `terminalResults`, `completionReceipts`, and `conversationHistory`
+(which can be empty). `historyBinding` is an optional runtime extension/profile,
+not a shared requirement for session-fixed effective ownership.
+
+Historical `1.0.0`, `1.1.0`, and `1.2.0` message/content validation is unchanged
+from the pre-widening proposal at `efed11f7786332d8bb0447ddbfc1727ddd7de09b`:
+roles exclude `developer`, function arguments are objects when present, and
+URI content requires `mediaType`. The root version selects historical
+`conversationEntry` definitions or the v2 definitions. Only v2 transcript entries
+and terminal responses use the expanded lossless shapes. This is not a
+historical-contract correction, and no persisted legacy bytes are rewritten.
+
+Major 2 is proposed because the authority for completion and replay changes,
+not merely because new optional properties appear. **Is a major version the
+right mechanism, or can maintainers enforce an equally safe same-major rollout
+gate?** This schema intentionally rejects unlisted versions, including future
+2.x versions; accepting them must be a deliberate semantic compatibility
+decision, not just a numeric SemVer comparison.
+
+At upstream main `62afdbac03f0a81b0917abe6328203b706a2f294`,
+Python's `DurableAgentState.from_dict` checks for a version's presence but does
+not gate its value, and `DurableAgentStateData.from_dict` reads the transcript
+without retaining unknown data-level fields. This is a compatibility gap to
+resolve jointly, not a criticism or a claim that Python already supports 2.0.
+The revised C# preview instead rejects unsupported versions; its acceptance
+rules are not a shared runtime guarantee. A new major number alone does not
+protect deployments whose existing readers do not enforce it.
+
+## Proposed wire concepts and semantic invariants
+
+| Field | Proposed meaning |
+| --- | --- |
+| `terminalResults[correlationId]` | Immutable terminal response/error envelope, detached from transcript retention. |
+| `completionReceipts[correlationId]` | Independent completion evidence, retained after payload expiry and transcript pruning. |
+| Receipt `resultState` | `available` with a matching payload, or `unavailable` with a removal timestamp. |
+| `historyBinding` | Optional, separately versioned runtime extension/profile; preserved without imposing shared effective-owner semantics. |
+| `conversationHistory` | Evictable transcript, never the authoritative completion index in 2.0. |
+
+The schema validates local shape, not all cross-object or temporal invariants.
+Any future implementation must additionally enforce:
+
+- Keys equal the embedded `correlationId`, compared exactly and case-sensitively
+  without normalization, within one durable entity/session generation.
+  When present on a v2 request, response, or error response, the transcript
+  `correlationId` uses the same `identifier` constraints as the result maps.
+  Legacy entry handling is unchanged; compaction still has no correlation.
+  Request identities must not be reused for different work in that generation.
+  Every terminal result has exactly one matching receipt. Outcome, completion
+  instant, and expiry instant (including absence) agree between them.
+- Terminal result contents and receipt identity/outcome/completion/expiry are
+  immutable. At the entity operation boundary, the result and receipt must
+  commit atomically with that operation's session/continuation, ingestion,
+  entity-local transcript, TTL, binding, and other local control-state changes.
+  They must not commit independently of the corresponding local state.
+  External provider writes and tool effects are outside this local transaction,
+  as discussed in the [ADR](https://github.com/microsoft/agent-framework-durable-extension/pull/88).
+  Availability can transition only from `available` to `unavailable`,
+  atomically removing the result and recording `resultUnavailableAt`; it never
+  reopens execution or changes a success into a failure.
+- An `available` receipt requires a result; an `unavailable` receipt forbids one.
+  No receipt means only **no recorded terminal completion**. It means pending
+  only for a request independently known to have been accepted; unknown request
+  identities are not automatically pending. This proposal adds no request
+  admission registry and makes no exactly-once claim for external side effects.
+- `resultExpiresAt`, when present, is no earlier than `completedAt`. At or after
+  that instant a poller must report completed-but-result-unavailable even if a
+  lazy cleanup has not yet removed a stored `available` payload. It must not
+  deliver the expired payload, report pending, or rerun the request.
+  `resultUnavailableAt` is no earlier than completion; for a time-expired
+  payload it is no earlier than expiry. `unavailable` can also represent an
+  agreed explicit removal policy; absence of `resultExpiresAt` is not a
+  guarantee against such removal.
+- Receipts survive payload expiry and transcript pruning for the agreed
+  duplicate-delivery lifetime. No receipt eviction or session-ID reuse policy
+  is specified here. Whole-entity TTL/deletion and receipt storage growth must
+  be resolved before deployment, not silently treated as transcript retention.
+
+Expired lookup reports completed-but-result-unavailable plus the retained
+`succeeded` or `failed` outcome, with no expired payload and no reopening of
+execution. This agreed contract behavior still requires aligned ADR wording
+and a Python receipt/lookup update; it is not a claim about current Python
+behavior or authorization to emit 2.0.
+
+An older receipt without an authoritative outcome must **not** be assigned
+`succeeded` or `failed` from absence of an error, a pruned transcript, expiry,
+or a default. Preserve its known completion/unavailability facts without
+inventing an outcome or rerunning the work. The required v2 receipt `outcome`
+may be populated only from authoritative evidence; absent that evidence, the
+legacy receipt cannot be promoted to this v2 shape. A separately agreed legacy
+lookup/migration representation must retain the distinction. This proposal
+does not add a fabricated `unknown` outcome to the v2 enum.
+
+The proposed envelope requires `response.messages` for success and failure
+(an empty list is allowed). Failure additionally requires `error.code` and
+`error.message`; success forbids `error`. Error details and response metadata
+are JSON only. A failure's partial messages are diagnostic output, not an
+instruction to replay a failed turn. Whether failures should instead use an
+error-only union, and how cancellation is represented, remain review questions.
+
+`response.value` is an optional, named caller-visible JSON result, independent
+of messages and text. An absent field means no structured value; explicit
+`null`, `false`, `0`, `""`, `[]`, and `{}` are present values and must survive
+round-tripping without truthiness-based omission. No separate presence flag
+is needed. Consumers must not infer `value` from text, coerce its type, or
+serialize arbitrary model/runtime objects. Unknown nested properties remain
+part of the value. The same JSON preservation rule applies if a failed response
+carries a diagnostic value; its outcome remains failed.
+
+### Optional runtime extension/profile
+
+Stable provider/configuration identity is distinct from effective per-run
+history ownership. The shared contract **does not require session-fixed
+effective ownership** and must not prohibit Python's supported per-run
+transitions. C# may separately enforce a fixed-owner policy/profile.
+
+`historyBinding` now denotes an optional, separately versioned runtime
+extension/profile rather than a standardized shared binding object. The existing
+spelling is retained to avoid moving stored data; there is no new shared
+`providerBinding` or `configurationBinding` definition. Compatible writers must
+preserve the original JSON value and all nested fields, even when they do not
+understand or use that profile. The shared schema intentionally does not validate
+its internal shape, version, owner kinds, or provider keys.
+
+A runtime that relies on the profile for restoration must validate the profile
+identity, supported version, required fields, and applicable policy before use,
+using trusted configuration rather than dynamically activating types from JSON.
+Unsupported or malformed profiles must fail that runtime's restoration path;
+they must not be silently ignored when the runtime depends on them. Other
+consumers preserve the data without treating shared-schema validation as profile
+approval. Even null or a malformed profile can be preserved as opaque JSON;
+that does not make it usable by a relying runtime.
+
+The `version`, `ownerKind`, and non-secret logical `providerKey` in existing
+synthetic fixtures illustrate one runtime profile, not a shared mandatory shape.
+Profile-specific fixed ownership remains runtime policy. Absence implies neither
+a default owner nor permission to infer one from opaque session state. No profile
+is an authorization grant. A shared descriptor can be proposed later when there
+is a concrete common consumer; no effective-owner transition protocol is imposed.
+
+## Existing state, extension data, and trust boundaries
+
+`session` is opaque JSON continuation/provider state. Preserve it, but do not
+infer an owner or instantiate a runtime type from its contents. The optional
+terminal `continuationToken` is base64 bytes; cross-language encoding does not
+prove cross-provider resumability. Its byte contract needs joint agreement.
+
+`expirationTimeUtc` documents the existing whole-entity idle TTL field; absent
+or null means no stored deadline. Deleting the entity also deletes receipts:
+this is distinct from `resultExpiresAt` and ends any in-entity deduplication
+evidence. An external tombstone, bounded request lifetime, or session-generation
+policy must address late duplicates before such deletion is compatible with 2.0.
+
+`ingestedPositions` is a legacy highest-seen position by producer, **not proof
+of a contiguous delivered prefix**, an exact receipt set, or terminal completion.
+Migration must preserve its historical meaning and cannot infer that gaps were
+delivered. After delivering `[1, 3]`, selecting `[2, 4]` must deliver both while
+remembering that `3` was delivered. A scalar `3` alone cannot establish that.
+Exact gap-preserving workflow receipt sets or ranges need separately versioned
+bookkeeping with explicit producer/delivery identity, preservation, and migration
+semantics, independent of transcript retention. This proposal neither invents
+that wire format nor backfills receipts from the scalar.
+
+`truncation` records evicted message count and first/last eviction
+instants (last must be no earlier than first). It is diagnostic evidence, not
+model context. Optional `messageId` is message identity, not request identity.
+
+### Lossless messages and JSON content
+
+For schema 2.0 only, message roles include `developer`. Function-call `arguments` accepts the
+original object or string; preserve the entire string, including whitespace
+and incomplete/non-JSON text, without parsing it into an object. URI content
+requires a URI but not a media type; absence stays absent rather than being
+filled with guessed metadata. Versioned message/content definitions keep these
+expansions out of historical 1.x validation, including when the same message is
+placed in a request, response, error response, or compaction transcript entry.
+The terminal-response message path also uses the v2 definitions.
+
+For supported content not represented by a typed definition, a producer may
+use the explicit `{"$type":"unknown","content":...}` wrapper with the complete
+original JSON value, including its metadata. An opaque payload with its own
+`type` or `$type` remains data and must not select or activate runtime types.
+Only a safe, explicit JSON representation qualifies; no arbitrary object
+reflection, `repr` fallback, or executable serialization is implied. If a
+supported value cannot be preserved safely, report the incompatibility rather
+than silently dropping it or claiming a lossless terminal result was persisted.
+The v2 lossless producer-mapping requirement does not widen the old explicit
+`unknown.content` JSON shape: arbitrary JSON inside that wrapper was already
+valid historically and remains valid. Historical consumers are not newly
+required to understand v2 producer mappings.
+
+Lossless here means JSON value preservation, including array order, exact
+string contents, numeric fidelity, and absent versus null fields. It does not
+require byte-identical JSON formatting or object-property order. Wrapping is a
+producer mapping for supported unmodeled content, not permission for a reader
+to hide malformed known wire fields or accept unknown wire discriminators.
+
+Unknown properties are allowed and must round-trip **at their original object
+locations**, independently of explicit `extensionData` objects, including
+nested content and mailbox fields. Known fields must still satisfy their
+declared types; do not hide malformed values in extension data. This preservation
+rule is a requirement on future compatible readers/writers, not a description
+of every current serializer. Metadata cannot override known envelope fields.
+
+Unknown properties are not unknown discriminators: 2.0 accepts only transcript
+`$type` values `request`, `response`, `errorResponse`, and `compaction`.
+Compaction has no `correlationId`. Content `$type` values are `data`, `error`,
+`functionCall`, `functionResult`, `hostedFile`, `hostedVectorStore`, `usage`,
+`text`, `reasoning`, `uri`, and the explicit `unknown` wrapper. Unsupported
+versions, outcomes, availability values, roles,
+or discriminators must be rejected for processing, not silently converted to
+success or to an empty unknown-content wrapper. Opaque `unknown.content` itself
+can be any JSON value, including null; `$runtimeType` inside it is just data.
+Runtime-profile discriminators and versions are different: validate them only
+when relying on that profile, and otherwise preserve them without interpretation.
+
+Persisted JSON is untrusted data. Never dynamically load types, follow URIs,
+execute tool calls, or log opaque session/error/token contents merely by reading
+state. Normal host authorization, redaction, and total storage/depth limits are
+still required. Identifier limits count Unicode code points, not UTF-16 units.
+Identifiers are nonblank and exclude C0/C1 controls; metadata is not executable.
+Usage metadata retains arbitrary JSON even if a runtime cannot represent it as
+numeric counts. Integer ranges, timestamp precision, and provider-specific
+continuation formats require cross-language agreement; validation alone does
+not ensure lossless projection. No provider or retention policy is implemented.
+
+## Rollout, migration, and maintainer questions
+
+Before any runtime emits 2.0, agree on and enforce a deployment floor covering
+state readers, duplicate lookups, pollers, writers, rollback writers, hosting
+consumers, and tools such as the scheduler dashboard. Participants that may
+process 2.0 must implement its behavior; others must reject it before processing
+or mutation and be isolated from 2.0 routing. Merely preserving fields is not
+enough. Rollback to a transcript-only writer must be prevented once 2.0 exists.
+
+Do not migrate by changing only `schemaVersion` or by adding empty receipt maps
+to previously used 1.x state. Pruned transcript cannot prove prior completion
+or reconstruct immutable responses. Migration needs authoritative completion
+evidence or an explicitly isolated new session generation with agreed duplicate
+handling. This PR contains neither a migration nor code to enable revised writes.
+
+Feedback requested from Ahmed/Python maintainers and .NET/Durable Task maintainers:
+
+1. Schema shape, correlation scope, major 2 versus an enforceable same-major gate.
+2. Runtime-specific profile definitions and restoration validation, without
+   imposing session-fixed ownership as a shared rule.
+3. Success/error envelope, cancellation, and continuation-byte interoperability.
+4. Legacy receipt representation when authoritative outcome is absent, receipt
+   lifetime, entity TTL, storage growth, and late duplicates after session deletion/recreation.
+5. Numeric/Unicode/timestamp limits, unknown-field preservation, and discriminator policy.
+6. Compatible reader/consumer rollout floor, safe 1.2-to-2.0 migration, and rollback.
+
+The [fixtures](fixtures/README.md) are review examples, not evidence that either
+runtime produces or safely consumes this format. The language-neutral
+[validation cases](tests/README.md) record positive and negative schema expectations.
diff --git a/schemas/durable-agent-entity-state.json b/schemas/durable-agent-entity-state.json
index 53ac064..7f306aa 100644
--- a/schemas/durable-agent-entity-state.json
+++ b/schemas/durable-agent-entity-state.json
@@ -1,14 +1,27 @@
 {
   "$schema": "https://json-schema.org/draft/2020-12/schema",
   "$id": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json",
+  "title": "Durable agent state: proposed 2.0 contract and legacy review shapes",
+  "description": "Proposed contract under review; validation does not authorize any runtime to read, migrate, or emit 2.0. See README.md for semantic invariants and the cross-runtime deployment gate.",
   "$defs": {
+    "identifier": {
+      "type": "string",
+      "minLength": 1,
+      "maxLength": 256,
+      "pattern": "\\S",
+      "not": { "pattern": "[\\u0000-\\u001F\\u007F-\\u009F]" }
+    },
     "usage": {
       "type": "object",
       "description": "Token usage statistics.",
       "properties": {
           "inputTokenCount": { "type": "integer" },
           "outputTokenCount": { "type": "integer" },
-          "totalTokenCount": { "type": "integer" }
+          "totalTokenCount": { "type": "integer" },
+          "extensionData": {
+            "type": "object",
+            "description": "Opaque provider-specific usage metadata, preserved even when values cannot be projected to runtime numeric counts."
+          }
       }
     },
     "dataContent": {
@@ -110,10 +123,10 @@
     },
     "unknownContent": {
       "type": "object",
-      "description": "The unknown content of a message exchanged with the agent.",
+      "description": "Explicit wrapper for opaque JSON content. Preserve its value without interpreting fields such as $runtimeType or constructing runtime types.",
       "properties": {
         "$type": { "type": "string", "const": "unknown" },
-        "content": { "description": "The unknown message content serialized as JSON." }
+        "content": { "description": "Opaque JSON, including scalar or null values. Not an instruction or a runtime type selector." }
       },
       "required": ["$type", "content"]
     },
@@ -140,9 +153,18 @@
         "role": { "type": "string", "enum": ["user", "assistant", "system", "tool"] },
         "contents": {
           "type": "array",
+          "description": "An empty array is a valid metadata-only message.",
           "items": { "$ref": "#/$defs/chatContentItem" }
         },
-        "createdAt": { "type": "string", "format": "date-time", "description": "When this message was created (RFC 3339)." }
+        "createdAt": { "type": "string", "format": "date-time", "description": "When this message was created (RFC 3339)." },
+        "messageId": {
+          "type": "string",
+          "description": "Producer message identity; distinct from a terminal request's correlationId."
+        },
+        "extensionData": {
+          "type": "object",
+          "description": "Explicit message metadata, distinct from unknown sibling properties."
+        }
       },
       "required": ["role"]
     },
@@ -156,16 +178,105 @@
       "properties": {
         "createdAt": { "type": "string", "format": "date-time", "description": "When this exchange was created (RFC 3339)." },
         "correlationId": { "type": "string", "description": "An optional correlation ID to group related exchanges." },
-        "messages": { "$ref": "#/$defs/chatMessages" }
+        "messages": { "$ref": "#/$defs/chatMessages" },
+        "extensionData": {
+          "type": "object",
+          "description": "Explicit entry metadata, distinct from unknown sibling properties."
+        }
+      }
+    },
+    "v2FunctionCallContent": {
+      "type": "object",
+      "description": "Schema 2.0 function call with lossless original argument form.",
+      "properties": {
+        "$type": { "type": "string", "const": "functionCall" },
+        "callId": { "type": "string", "description": "The identifier of the function being called." },
+        "name": { "type": "string", "description": "The name of the function being called." },
+        "arguments": {
+          "type": ["object", "string"],
+          "description": "Original function arguments. Preserve string form verbatim, including incomplete or non-JSON text; do not parse, normalize, or replace it with an object."
+        }
+      },
+      "required": ["$type", "callId", "name"]
+    },
+    "v2UriContent": {
+      "type": "object",
+      "description": "Schema 2.0 URI content; absent media type remains absent.",
+      "properties": {
+        "$type": { "type": "string", "const": "uri" },
+        "uri": { "type": "string", "description": "The URI." },
+        "mediaType": { "type": "string", "description": "The media type of the URI, if supplied." }
+      },
+      "required": ["$type", "uri"]
+    },
+    "v2UnknownContent": {
+      "$ref": "#/$defs/unknownContent",
+      "description": "Schema 2.0 lossless producer mapping for supported unmodeled JSON content. Preserve the complete original JSON value and metadata without interpreting fields such as $runtimeType or constructing runtime types. Not a fallback for malformed known wire fields. The existing opaque wrapper's accepted JSON shapes are unchanged."
+    },
+    "v2ChatContentItem": {
+      "oneOf": [
+        { "$ref": "#/$defs/dataContent" },
+        { "$ref": "#/$defs/errorContent" },
+        { "$ref": "#/$defs/v2FunctionCallContent" },
+        { "$ref": "#/$defs/functionResultContent" },
+        { "$ref": "#/$defs/hostedFileContent" },
+        { "$ref": "#/$defs/hostedVectorStoreContent" },
+        { "$ref": "#/$defs/usageContent" },
+        { "$ref": "#/$defs/textContent" },
+        { "$ref": "#/$defs/textReasoningContent" },
+        { "$ref": "#/$defs/v2UriContent" },
+        { "$ref": "#/$defs/v2UnknownContent" }
+      ]
+    },
+    "v2ChatMessage": {
+      "type": "object",
+      "description": "Schema 2.0 chat message. Historical versions continue to use chatMessage.",
+      "properties": {
+        "authorName": { "type": "string", "description": "The name of the author of the message." },
+        "role": { "type": "string", "enum": ["user", "assistant", "system", "developer", "tool"] },
+        "contents": {
+          "type": "array",
+          "description": "An empty array is a valid metadata-only message.",
+          "items": { "$ref": "#/$defs/v2ChatContentItem" }
+        },
+        "createdAt": { "type": "string", "format": "date-time", "description": "When this message was created (RFC 3339)." },
+        "messageId": {
+          "type": "string",
+          "description": "Producer message identity; distinct from a terminal request's correlationId."
+        },
+        "extensionData": {
+          "type": "object",
+          "description": "Explicit message metadata, distinct from unknown sibling properties."
+        }
+      },
+      "required": ["role"]
+    },
+    "v2ChatMessages": {
+      "type": "array",
+      "description": "Ordered list of schema 2.0 chat messages.",
+      "items": { "$ref": "#/$defs/v2ChatMessage" }
+    },
+    "v2ConversationEntry": {
+      "type": "object",
+      "properties": {
+        "createdAt": { "type": "string", "format": "date-time", "description": "When this exchange was created (RFC 3339)." },
+        "correlationId": { "type": "string", "description": "An optional correlation ID to group related exchanges." },
+        "messages": { "$ref": "#/$defs/v2ChatMessages" },
+        "extensionData": {
+          "type": "object",
+          "description": "Explicit entry metadata, distinct from unknown sibling properties."
+        }
       }
     },
     "agentRequest": {
       "allOf": [
-        { "$ref": "#/$defs/conversationEntry" }
+        { "$ref": "#/$defs/v2ConversationEntry" }
       ],
       "description": "The request (i.e. prompt) sent to the agent.",
+      "required": ["$type"],
       "properties": {
         "$type": { "type": "string", "const": "request" },
+        "correlationId": { "$ref": "#/$defs/identifier" },
         "orchestrationId": {
           "type": "string",
           "description": "The identifier of the orchestration that initiated this agent request (if any)."
@@ -182,36 +293,245 @@
     },
     "agentResponse": {
       "allOf": [
-        { "$ref": "#/$defs/conversationEntry" }
+        { "$ref": "#/$defs/v2ConversationEntry" }
       ],
       "description": "The response received from the agent.",
+      "required": ["$type"],
       "properties": {
         "$type": { "type": "string", "const": "response" },
+        "correlationId": { "$ref": "#/$defs/identifier" },
         "usage": {
           "$ref": "#/$defs/usage"
         }
       }
     },
+    "agentErrorResponse": {
+      "allOf": [
+        { "$ref": "#/$defs/v2ConversationEntry" }
+      ],
+      "description": "Diagnostic record of a failed turn, not model replay context or authoritative completion evidence.",
+      "required": ["$type"],
+      "properties": {
+        "$type": { "type": "string", "const": "errorResponse" },
+        "correlationId": { "$ref": "#/$defs/identifier" },
+        "usage": { "$ref": "#/$defs/usage" }
+      }
+    },
+    "compaction": {
+      "allOf": [
+        { "$ref": "#/$defs/v2ConversationEntry" }
+      ],
+      "description": "Compacted model context; it answers no request and has no correlationId.",
+      "required": ["$type"],
+      "properties": {
+        "$type": { "type": "string", "const": "compaction" },
+        "correlationId": false
+      }
+    },
+    "terminalResponse": {
+      "type": "object",
+      "description": "JSON-only terminal response projection. No raw runtime object graph is persisted.",
+      "properties": {
+        "messages": { "$ref": "#/$defs/v2ChatMessages" },
+        "value": {
+          "type": ["null", "boolean", "number", "string", "array", "object"],
+          "description": "Optional caller-visible structured JSON result, independent of messages. Absence means no structured value; explicit null, false, zero, empty strings, arrays, and objects remain present values. No runtime object serialization or inferred value from message text."
+        },
+        "usage": { "$ref": "#/$defs/usage" },
+        "createdAt": { "type": "string", "format": "date-time" },
+        "responseId": { "$ref": "#/$defs/identifier" },
+        "agentId": { "$ref": "#/$defs/identifier" },
+        "finishReason": { "$ref": "#/$defs/identifier" },
+        "continuationToken": {
+          "type": "string",
+          "maxLength": 16384,
+          "contentEncoding": "base64",
+          "pattern": "^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$",
+          "not": { "pattern": "[^A-Za-z0-9+/=]" },
+          "description": "Opaque base64-encoded continuation bytes. Encoding alone does not imply that another runtime or provider can resume them."
+        },
+        "extensionData": {
+          "type": "object",
+          "description": "Explicit JSON response metadata; preserve separately from unknown sibling properties.",
+          "propertyNames": { "$ref": "#/$defs/identifier" }
+        }
+      },
+      "required": ["messages"],
+      "additionalProperties": true
+    },
+    "terminalError": {
+      "type": "object",
+      "description": "Sanitized JSON terminal failure metadata, not a serialized exception or executable type.",
+      "properties": {
+        "code": { "$ref": "#/$defs/identifier" },
+        "message": {
+          "type": "string",
+          "minLength": 1,
+          "maxLength": 16384,
+          "pattern": "\\S"
+        },
+        "details": { "description": "Optional JSON failure details; subject to privacy and storage limits." }
+      },
+      "required": ["code", "message"],
+      "additionalProperties": true
+    },
+    "terminalResult": {
+      "type": "object",
+      "description": "Immutable terminal result detached from conversationHistory. Map-key equality and receipt consistency require semantic validation.",
+      "properties": {
+        "correlationId": { "$ref": "#/$defs/identifier" },
+        "outcome": { "type": "string", "enum": ["succeeded", "failed"] },
+        "completedAt": { "type": "string", "format": "date-time" },
+        "resultExpiresAt": { "type": "string", "format": "date-time" },
+        "response": { "$ref": "#/$defs/terminalResponse" },
+        "error": { "$ref": "#/$defs/terminalError" }
+      },
+      "required": ["correlationId", "outcome", "completedAt", "response"],
+      "allOf": [
+        {
+          "if": { "properties": { "outcome": { "const": "succeeded" } } },
+          "then": { "not": { "required": ["error"] } }
+        },
+        {
+          "if": { "properties": { "outcome": { "const": "failed" } } },
+          "then": { "required": ["error"] }
+        }
+      ],
+      "additionalProperties": true
+    },
+    "completionReceipt": {
+      "type": "object",
+      "description": "Completion evidence surviving result expiry. Identity, authoritative outcome, completion time, and expiry policy are immutable; availability may transition once from available to unavailable. Expired lookup retains outcome without a payload. An older receipt lacking authoritative outcome cannot be promoted to this shape by inventing succeeded or failed.",
+      "properties": {
+        "correlationId": { "$ref": "#/$defs/identifier" },
+        "outcome": { "type": "string", "enum": ["succeeded", "failed"] },
+        "completedAt": { "type": "string", "format": "date-time" },
+        "resultState": { "type": "string", "enum": ["available", "unavailable"] },
+        "resultExpiresAt": { "type": "string", "format": "date-time" },
+        "resultUnavailableAt": { "type": "string", "format": "date-time" }
+      },
+      "required": ["correlationId", "outcome", "completedAt", "resultState"],
+      "allOf": [
+        {
+          "if": { "properties": { "resultState": { "const": "available" } } },
+          "then": { "not": { "required": ["resultUnavailableAt"] } }
+        },
+        {
+          "if": { "properties": { "resultState": { "const": "unavailable" } } },
+          "then": { "required": ["resultUnavailableAt"] }
+        }
+      ],
+      "additionalProperties": true
+    },
+    "historyBinding": {
+      "description": "Optional separately versioned runtime extension/profile, not a shared binding object or effective-owner policy. The existing field name is retained for preservation. Compatible writers preserve the original JSON value; only a runtime relying on it validates its recognized profile and version before use. Shared shape validation does not imply the value is a usable profile."
+    },
     "data": {
       "type": "object",
       "description": "The durable agent's state data.",
       "properties": {
         "conversationHistory": {
           "type": "array",
-          "description": "Ordered list of conversation entries.",
-          "items": { "$ref": "#/$defs/conversationEntry" }
+          "description": "Ordered, evictable transcript. The root schemaVersion selects historical conversationEntry items or the known schema 2.0 entry definitions."
+        },
+        "terminalResults": {
+          "type": "object",
+          "description": "Immutable results keyed by exact, case-sensitive request correlationId within this entity/session generation.",
+          "propertyNames": { "$ref": "#/$defs/identifier" },
+          "additionalProperties": { "$ref": "#/$defs/terminalResult" }
+        },
+        "completionReceipts": {
+          "type": "object",
+          "description": "Terminal evidence keyed by correlationId; independent of transcript and result-payload retention.",
+          "propertyNames": { "$ref": "#/$defs/identifier" },
+          "additionalProperties": { "$ref": "#/$defs/completionReceipt" }
+        },
+        "historyBinding": { "$ref": "#/$defs/historyBinding" },
+        "session": {
+          "type": "object",
+          "description": "Opaque JSON session continuation and provider state. Preserve without using its fields to select or construct runtime types."
+        },
+        "expirationTimeUtc": {
+          "type": ["string", "null"],
+          "format": "date-time",
+          "description": "Existing whole-entity idle TTL deadline, not result expiry. Absent or null means no stored deadline. Whole-entity deletion removes receipts too; a separate deduplication-lifetime agreement is required."
+        },
+        "ingestedPositions": {
+          "type": "object",
+          "description": "Legacy highest-seen position by producer, not proof of a contiguous delivered prefix or request completion. Preserve historical values without inferring missing deliveries during migration. Exact gap-preserving workflow receipts require separately versioned bookkeeping independent of transcript retention.",
+          "additionalProperties": { "type": "integer", "minimum": 0 }
+        },
+        "truncation": {
+          "type": "object",
+          "description": "Diagnostic evidence of transcript removal; not model context or terminal completion evidence.",
+          "properties": {
+            "evictedMessageCount": { "type": "integer", "minimum": 1 },
+            "firstEvictedAt": { "type": "string", "format": "date-time" },
+            "lastEvictedAt": { "type": "string", "format": "date-time" }
+          },
+          "required": ["evictedMessageCount", "firstEvictedAt", "lastEvictedAt"]
+        },
+        "extensionData": {
+          "type": "object",
+          "description": "Explicit data metadata; preserve separately from unknown sibling properties."
         }
-      }
+      },
+      "additionalProperties": true
     }
   },
   "type": "object",
   "properties": {
     "schemaVersion": {
       "type": "string",
-      "description": "Semantic version of this state schema. By convention, this should be the first property.",
-      "pattern": "^\\d+\\.\\d+\\.\\d+$"
+      "description": "Exact review snapshots, not a runtime acceptance list. 1.2.0 and 2.0.0 are proposals; future versions require an explicit compatibility decision. By convention this is the first property.",
+      "enum": ["1.0.0", "1.1.0", "1.2.0", "2.0.0"]
     },
-    "data": { "$ref": "#/$defs/data" }
+    "data": { "$ref": "#/$defs/data" },
+    "extensionData": {
+      "type": "object",
+      "description": "Explicit root metadata; preserve separately from unknown sibling properties."
+    }
   },
-  "required": ["schemaVersion", "data"]
+  "required": ["schemaVersion", "data"],
+  "additionalProperties": true,
+  "allOf": [
+    {
+      "if": {
+        "properties": { "schemaVersion": { "const": "2.0.0" } }
+      },
+      "then": {
+        "properties": {
+          "data": {
+            "required": ["conversationHistory", "terminalResults", "completionReceipts"],
+            "properties": {
+              "conversationHistory": {
+                "items": {
+                  "oneOf": [
+                    { "$ref": "#/$defs/agentRequest" },
+                    { "$ref": "#/$defs/agentResponse" },
+                    { "$ref": "#/$defs/agentErrorResponse" },
+                    { "$ref": "#/$defs/compaction" }
+                  ]
+                }
+              }
+            }
+          }
+        }
+      },
+      "else": {
+        "properties": {
+          "data": {
+            "properties": {
+              "conversationHistory": {
+                "items": { "$ref": "#/$defs/conversationEntry" }
+              },
+              "terminalResults": false,
+              "completionReceipts": false,
+              "historyBinding": false
+            }
+          }
+        }
+      }
+    }
+  ]
 }
diff --git a/schemas/fixtures/README.md b/schemas/fixtures/README.md
new file mode 100644
index 0000000..07300c2
--- /dev/null
+++ b/schemas/fixtures/README.md
@@ -0,0 +1,69 @@
+# Durable agent state review fixtures
+
+All JSON files here are synthetic, language-neutral review data validated with
+the parent [Draft 2020-12 schema](../durable-agent-entity-state.json).
+They are not captured production state, generated serializer snapshots, or
+evidence of Python/.NET 2.0 support.
+
+| Fixture | Provenance and purpose |
+| --- | --- |
+| `shared-durable-agent-state-1.2-python-shape.json` | Reproduced from proposal commit `247bbdd60944d5ac93e79079803aa23e992d0369`. Modeled on parallel Python-shaped 1.2 work, with synthetic future fields and content for preservation review. **Not byte-for-byte output from the current Python serializer.** |
+| `shared-durable-agent-state-2.0.json` | Reproduced from the same proposal commit. Synthetic available success and expired failure receipt, detached from transcript responses; includes unknown mailbox/binding fields. |
+| `shared-durable-agent-state-2.0-pruned.json` | Authored for this contract-only proposal. Empty transcript with available failure, unavailable success, opaque session data, truncation evidence, and whole-entity TTL. Not a migration output. |
+| `shared-durable-agent-state-2.0-lossless.json` | Authored for review feedback. Synthetic developer-role request, verbatim string-form function arguments, URI without invented media type, complete opaque JSON content, explicit structured `false` value, and no binding. |
+
+The source proposal builds on `5de13e8d5dd4b4b76e7360e89ceeb3968a103781`;
+its runtime DTOs, converters, tests, and test-project fixture links are
+deliberately excluded. The corrected `python-shape` filename identifies
+provenance, not a promise of current serializer behavior. There is no fixture
+generator or test-project integration in this PR.
+
+The two reproduced source fixtures are unchanged as JSON values. The example
+bindings are optional runtime-profile data, not a shared binding shape or proof
+of session-fixed effective ownership. Compatible writers preserve them; only a
+runtime relying on a profile validates its identity, version, shape, and policy.
+The original legacy fixture stays valid under the unchanged historical message
+definitions. The expanded lossless fixture is v2-only; its persisted bytes are
+unchanged too.
+
+For `shared-durable-agent-state-2.0.json`, interpret the example at
+`2026-09-10T05:00:05Z`: `corr-2` has an available result and `corr-expired`
+proves completed failure without a payload. After `corr-2`'s expiry a compatible
+poller must report completed-but-result-unavailable even before cleanup.
+
+For `shared-durable-agent-state-2.0-pruned.json`, interpret the example at
+`2026-09-10T06:00:05Z`: `corr-failed` has an available failure payload and
+`corr-pruned` proves completed success without one. Transcript removal did not
+erase either completion. `expirationTimeUtc` is a separate whole-entity deadline,
+not a proposed resolution of tombstone lifetime after entity deletion.
+
+The lossless fixture intentionally contains incomplete function-argument text.
+The exact string must survive; parsing it, completing the JSON, or replacing it
+with an object would lose information. The URI has no `mediaType` to infer. The
+opaque content's nested `$type` and `$runtimeType` are inert JSON, including all
+metadata, not type-activation instructions. `response.value: false` is a present
+structured result; the earlier fixtures omit `value`. Null, zero, and empty
+values have separate [validation cases](../tests/README.md).
+
+The lossless fixture's scalar `ingestedPositions["legacy-producer"] = 3` records
+only highest-seen position. It does not say whether `2` was delivered. None of
+these fixtures defines or infers a gap-preserving workflow receipt set.
+
+The expired receipts retain `outcome`; lookup reports that retained outcome with
+completed-but-result-unavailable, without restoring a payload or reopening
+execution. This contract still requires the corresponding ADR/Python updates.
+No fixture claims that a legacy receipt without authoritative outcome can be
+converted by inventing success or failure. Such a receipt cannot satisfy the
+v2 required-outcome shape without authoritative evidence.
+
+For an identity absent from the receipt maps, the examples show only the
+absence of recorded completion: a separately accepted request may be pending,
+whereas an unrecognized identity remains unknown. No fixture invents an
+admission registry, claims exactly-once external side effects, or authorizes
+schema-version-only migration. The 1.2 and 2.0 examples are independent
+snapshots, not a before/after pair with inferred completion evidence.
+
+Validation must enable Draft 2020-12 and date-time format checking, then check
+the cross-map/time invariants in [the proposal](../README.md). JSON Schema alone
+cannot enforce key equality, atomicity, historical immutability, expiry relative
+to a clock, or compatibility of a deployed reader.
diff --git a/schemas/fixtures/shared-durable-agent-state-1.2-python-shape.json b/schemas/fixtures/shared-durable-agent-state-1.2-python-shape.json
new file mode 100644
index 0000000..ada0f64
--- /dev/null
+++ b/schemas/fixtures/shared-durable-agent-state-1.2-python-shape.json
@@ -0,0 +1,168 @@
+{
+  "schemaVersion": "1.2.0",
+  "data": {
+    "conversationHistory": [
+      {
+        "$type": "request",
+        "correlationId": "corr-python",
+        "createdAt": "2026-07-27T12:34:50+00:00",
+        "messages": [
+          {
+            "role": "user",
+            "messageId": "producer-request-id",
+            "extensionData": {
+              "origin": "python"
+            },
+            "contents": [
+              {
+                "$type": "text",
+                "text": "hello"
+              }
+            ]
+          }
+        ],
+        "extensionData": {
+          "requestFuture": true
+        }
+      },
+      {
+        "$type": "response",
+        "correlationId": "corr-python",
+        "createdAt": "2026-07-27T12:34:51+00:00",
+        "messages": [
+          {
+            "role": "assistant",
+            "authorName": "python-agent",
+            "createdAt": "2026-07-27T12:34:51+00:00",
+            "messageId": "python-metadata-only",
+            "extensionData": {
+              "metadataOrigin": "python"
+            },
+            "contents": []
+          },
+          {
+            "role": "assistant",
+            "contents": [
+              {
+                "$type": "text",
+                "text": "world"
+              }
+            ]
+          },
+          {
+            "role": "assistant",
+            "contents": [
+              {
+                "$type": "reasoning",
+                "text": "private reasoning"
+              }
+            ]
+          },
+          {
+            "role": "assistant",
+            "messageId": "python-unknown-content",
+            "contents": [
+              {
+                "$type": "unknown",
+                "content": {
+                  "$runtimeType": "python-owned-user-field",
+                  "type": "future_python_content",
+                  "payload": "python-value",
+                  "annotations": [
+                    {
+                      "kind": "citation",
+                      "value": "python-ref"
+                    }
+                  ],
+                  "additional_properties": {
+                    "producer": "python"
+                  },
+                  "future_payload": {
+                    "nested": [
+                      1,
+                      2,
+                      3
+                    ]
+                  }
+                }
+              }
+            ]
+          }
+        ],
+        "usage": {
+          "inputTokenCount": 4,
+          "outputTokenCount": 2,
+          "totalTokenCount": 6,
+          "extensionData": {
+            "providerCount": 7,
+            "futureNumeric": 11,
+            "futureString": "seven",
+            "futureObject": {
+              "count": 8
+            },
+            "futureArray": [
+              9
+            ]
+          }
+        }
+      },
+      {
+        "$type": "errorResponse",
+        "correlationId": "corr-error",
+        "createdAt": "2026-07-27T12:34:52+00:00",
+        "messages": [
+          {
+            "role": "assistant",
+            "contents": [
+              {
+                "$type": "error",
+                "message": "failed",
+                "errorCode": "Example"
+              }
+            ]
+          }
+        ]
+      },
+      {
+        "$type": "compaction",
+        "createdAt": "2026-07-27T12:34:56.123456+00:00",
+        "messages": [
+          {
+            "role": "assistant",
+            "contents": [
+              {
+                "$type": "text",
+                "text": "summary"
+              }
+            ]
+          }
+        ]
+      }
+    ],
+    "session": {
+      "type": "session",
+      "session_id": "@dafx-agent@session",
+      "state": {
+        "custom": {
+          "value": 1
+        }
+      }
+    },
+    "ingestedPositions": {
+      "input": 0,
+      "writer": 3
+    },
+    "extensionData": {
+      "dataProducer": "python"
+    },
+    "futureDataProperty": {
+      "preserve": true
+    }
+  },
+  "extensionData": {
+    "rootProducer": "interop-fixture"
+  },
+  "futureRootProperty": {
+    "preserve": true
+  }
+}
diff --git a/schemas/fixtures/shared-durable-agent-state-2.0-lossless.json b/schemas/fixtures/shared-durable-agent-state-2.0-lossless.json
new file mode 100644
index 0000000..a0b79df
--- /dev/null
+++ b/schemas/fixtures/shared-durable-agent-state-2.0-lossless.json
@@ -0,0 +1,77 @@
+{
+  "schemaVersion": "2.0.0",
+  "data": {
+    "conversationHistory": [
+      {
+        "$type": "request",
+        "correlationId": "corr-lossless",
+        "messages": [
+          {
+            "role": "developer",
+            "contents": [
+              {
+                "$type": "text",
+                "text": "Preserve the original result."
+              }
+            ]
+          }
+        ]
+      }
+    ],
+    "terminalResults": {
+      "corr-lossless": {
+        "correlationId": "corr-lossless",
+        "outcome": "succeeded",
+        "completedAt": "2026-09-11T10:00:00Z",
+        "response": {
+          "messages": [
+            {
+              "role": "assistant",
+              "contents": [
+                {
+                  "$type": "functionCall",
+                  "callId": "tool-example",
+                  "name": "example_tool",
+                  "arguments": " { \"partial\": "
+                },
+                {
+                  "$type": "uri",
+                  "uri": "https://example.test/media/1"
+                },
+                {
+                  "$type": "unknown",
+                  "content": {
+                    "$type": "example_unmodeled_media",
+                    "$runtimeType": "opaque-data-only",
+                    "bytes": "AQID",
+                    "metadata": {
+                      "presentNull": null,
+                      "empty": [],
+                      "annotations": [
+                        {
+                          "kind": "synthetic"
+                        }
+                      ]
+                    }
+                  }
+                }
+              ]
+            }
+          ],
+          "value": false
+        }
+      }
+    },
+    "completionReceipts": {
+      "corr-lossless": {
+        "correlationId": "corr-lossless",
+        "outcome": "succeeded",
+        "completedAt": "2026-09-11T10:00:00Z",
+        "resultState": "available"
+      }
+    },
+    "ingestedPositions": {
+      "legacy-producer": 3
+    }
+  }
+}
diff --git a/schemas/fixtures/shared-durable-agent-state-2.0-pruned.json b/schemas/fixtures/shared-durable-agent-state-2.0-pruned.json
new file mode 100644
index 0000000..6ac7777
--- /dev/null
+++ b/schemas/fixtures/shared-durable-agent-state-2.0-pruned.json
@@ -0,0 +1,59 @@
+{
+  "schemaVersion": "2.0.0",
+  "data": {
+    "conversationHistory": [],
+    "terminalResults": {
+      "corr-failed": {
+        "correlationId": "corr-failed",
+        "outcome": "failed",
+        "completedAt": "2026-09-10T06:00:00Z",
+        "response": {
+          "messages": []
+        },
+        "error": {
+          "code": "example_dependency_unavailable",
+          "message": "The example dependency could not complete the request.",
+          "details": {
+            "synthetic": true
+          }
+        }
+      }
+    },
+    "completionReceipts": {
+      "corr-failed": {
+        "correlationId": "corr-failed",
+        "outcome": "failed",
+        "completedAt": "2026-09-10T06:00:00Z",
+        "resultState": "available"
+      },
+      "corr-pruned": {
+        "correlationId": "corr-pruned",
+        "outcome": "succeeded",
+        "completedAt": "2026-09-09T06:00:00Z",
+        "resultState": "unavailable",
+        "resultExpiresAt": "2026-09-10T06:00:00Z",
+        "resultUnavailableAt": "2026-09-10T06:00:01Z"
+      }
+    },
+    "historyBinding": {
+      "version": 1,
+      "ownerKind": "durableState",
+      "providerKey": "example.local-history.v1"
+    },
+    "session": {
+      "exampleContinuation": {
+        "cursor": "synthetic-cursor",
+        "$runtimeType": "opaque-user-data"
+      }
+    },
+    "expirationTimeUtc": "2026-10-10T06:00:00Z",
+    "ingestedPositions": {
+      "example-producer": 3
+    },
+    "truncation": {
+      "evictedMessageCount": 4,
+      "firstEvictedAt": "2026-09-10T06:00:02Z",
+      "lastEvictedAt": "2026-09-10T06:00:03Z"
+    }
+  }
+}
diff --git a/schemas/fixtures/shared-durable-agent-state-2.0.json b/schemas/fixtures/shared-durable-agent-state-2.0.json
new file mode 100644
index 0000000..3a2702d
--- /dev/null
+++ b/schemas/fixtures/shared-durable-agent-state-2.0.json
@@ -0,0 +1,100 @@
+{
+  "schemaVersion": "2.0.0",
+  "data": {
+    "conversationHistory": [
+      {
+        "$type": "request",
+        "correlationId": "corr-2",
+        "createdAt": "2026-09-10T05:00:00+00:00",
+        "messages": [
+          {
+            "role": "user",
+            "messageId": "request-2",
+            "contents": [
+              {
+                "$type": "text",
+                "text": "Generate the artifact."
+              }
+            ]
+          }
+        ]
+      }
+    ],
+    "terminalResults": {
+      "corr-2": {
+        "correlationId": "corr-2",
+        "outcome": "succeeded",
+        "completedAt": "2026-09-10T05:00:03+00:00",
+        "resultExpiresAt": "2026-09-11T05:00:03+00:00",
+        "response": {
+          "messages": [
+            {
+              "role": "assistant",
+              "authorName": "fixture-agent",
+              "messageId": "response-2",
+              "contents": [
+                {
+                  "$type": "text",
+                  "text": "Artifact generated."
+                },
+                {
+                  "$type": "uri",
+                  "uri": "https://example.test/artifacts/2",
+                  "mediaType": "application/json"
+                }
+              ]
+            }
+          ],
+          "usage": {
+            "inputTokenCount": 5,
+            "outputTokenCount": 3,
+            "totalTokenCount": 8
+          },
+          "createdAt": "2026-09-10T05:00:03+00:00",
+          "responseId": "response-id-2",
+          "agentId": "agent-id-2",
+          "finishReason": "stop",
+          "continuationToken": "AQID",
+          "extensionData": {
+            "region": "test",
+            "attempt": 1
+          },
+          "futureResponseField": {
+            "preserve": true
+          }
+        },
+        "futureResultField": "preserve"
+      }
+    },
+    "completionReceipts": {
+      "corr-2": {
+        "correlationId": "corr-2",
+        "outcome": "succeeded",
+        "completedAt": "2026-09-10T05:00:03+00:00",
+        "resultState": "available",
+        "resultExpiresAt": "2026-09-11T05:00:03+00:00",
+        "futureReceiptField": 7
+      },
+      "corr-expired": {
+        "correlationId": "corr-expired",
+        "outcome": "failed",
+        "completedAt": "2026-09-09T05:00:03+00:00",
+        "resultState": "unavailable",
+        "resultExpiresAt": "2026-09-10T05:00:03+00:00",
+        "resultUnavailableAt": "2026-09-10T05:00:04+00:00"
+      }
+    },
+    "historyBinding": {
+      "version": 1,
+      "ownerKind": "historyProvider",
+      "providerKey": "contoso.support-history.v1",
+      "futureBindingField": "preserve"
+    },
+    "futureDataField": {
+      "preserve": true
+    }
+  },
+  "futureRootField": {
+    "preserve": true
+  }
+}
diff --git a/schemas/tests/README.md b/schemas/tests/README.md
new file mode 100644
index 0000000..70a102a
--- /dev/null
+++ b/schemas/tests/README.md
@@ -0,0 +1,58 @@
+# Language-neutral schema validation cases
+
+`validation-cases.json` and `versioned-envelope-cases.json` record positive and negative review expectations using
+the JSON Schema Test Suite's group shape: `description`, `schema`, and `tests`;
+each test has `description`, `data`, and `valid`. These are test data, not durable
+state fixtures, product implementation, or runtime test-project integration.
+
+Resolve the canonical schema ID locally to `../durable-agent-entity-state.json`;
+do not fetch it from GitHub, which might contain a different revision. Use a
+Draft 2020-12 validator. The cases cover v2-only correlation constraints,
+unchanged legacy/compaction handling, opaque runtime profiles, v2 lossless
+message shapes, structured-value presence, and historical ingestion scalars.
+
+The versioned cases use complete root envelopes for every version rather than
+just testing `$defs` fragments. Historical `1.0.0`, `1.1.0`, and `1.2.0` reject
+the newly widened developer role, string-form function arguments, and URI content
+without media type; v2 accepts them in its transcript and terminal payload paths.
+Historical explicit `unknown` JSON was already valid and stays valid in all
+versions. The unchanged legacy fixture remains additional compatibility evidence.
+Profile cases distinguish opaque shared preservation from validation by a relying
+runtime. Outcome cases reject attempts to promote receipts lacking authoritative
+outcome into the required-outcome v2 shape; they do not implement migration.
+
+For example, from the repository root with an existing Python `jsonschema`
+installation, this PowerShell command runs the structural cases without any
+network access or dependency installation:
+
+```powershell
+@'
+import json
+from pathlib import Path
+from jsonschema import Draft202012Validator
+from referencing import Registry, Resource
+
+schema = json.loads(Path(r"schemas\durable-agent-entity-state.json").read_text(encoding="utf-8"))
+Draft202012Validator.check_schema(schema)
+registry = Registry().with_resource(schema["$id"], Resource.from_contents(schema))
+count = 0
+for path in sorted(Path(r"schemas\tests").glob("*-cases.json")):
+    groups = json.loads(path.read_text(encoding="utf-8"))
+    for group in groups:
+        validator = Draft202012Validator(group["schema"], registry=registry)
+        for test in group["tests"]:
+            actual = validator.is_valid(test["data"])
+            if actual != test["valid"]:
+                raise AssertionError(f'{path.name}: {group["description"]}: {test["description"]}')
+            count += 1
+print(f"Passed {count} structural validation cases")
+'@ | python -
+```
+
+These cases have no timestamp-format assertions. Validate the separate state
+fixtures with date-time format checking as well as the cross-map/time invariants
+in the shared proposal. Test data alone cannot prove serializer round-tripping,
+atomic entity commits, per-run ownership transitions, or runtime lookup behavior.
+Future runtime implementations must additionally verify that original string
+arguments, absent media types, opaque JSON metadata, and all present `value`
+forms survive persistence without conversion, omission, or invented data.
diff --git a/schemas/tests/validation-cases.json b/schemas/tests/validation-cases.json
new file mode 100644
index 0000000..5eca503
--- /dev/null
+++ b/schemas/tests/validation-cases.json
@@ -0,0 +1,226 @@
+[
+  {
+    "description": "Version-scoped correlation IDs and optional binding",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json" },
+    "tests": [
+      {
+        "description": "V2 with empty transcript and no binding",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 request without a correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "request" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 response without a correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 error response without a correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "errorResponse" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 request with a valid correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "request", "correlationId": "Case-sensitive-id" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 response with a valid correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "correlationId": "Case-sensitive-id" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 error response with a valid correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "errorResponse", "correlationId": "Case-sensitive-id" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 blank request correlation is rejected",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "request", "correlationId": "" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "V2 whitespace response correlation is rejected",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "correlationId": "   " }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "V2 control-character error correlation is rejected",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "errorResponse", "correlationId": "id\u0000" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "V2 trailing newline correlation is rejected",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "request", "correlationId": "id\n" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "V2 null correlation is not omission",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "correlationId": null }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "Legacy blank correlation remains unchanged",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "$type": "request", "correlationId": "" }] } },
+        "valid": true
+      },
+      {
+        "description": "Legacy whitespace correlation remains unchanged",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "$type": "response", "correlationId": "   " }] } },
+        "valid": true
+      },
+      {
+        "description": "Proposed 1.2 control-character correlation remains unchanged",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "$type": "errorResponse", "correlationId": "id\u0000" }] } },
+        "valid": true
+      },
+      {
+        "description": "V2 compaction still has no correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "compaction" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 compaction rejects even a valid correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "compaction", "correlationId": "valid-id" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "Unknown V2 entry discriminator is rejected",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "future" }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "Shared validation preserves opaque profile data without approving it for restoration",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": {}, "historyBinding": {} } },
+        "valid": true
+      },
+      {
+        "description": "Opaque null profile is preserved, not interpreted as a usable profile",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": {}, "historyBinding": null } },
+        "valid": true
+      },
+      {
+        "description": "Binding remains forbidden in legacy state",
+        "data": { "schemaVersion": "1.2.0", "data": { "historyBinding": { "version": 1, "ownerKind": "historyProvider", "providerKey": "example.config" } } },
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "Schema 2.0 lossless message content",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json#/$defs/v2ChatMessage" },
+    "tests": [
+      { "description": "Developer role", "data": { "role": "developer", "contents": [] }, "valid": true },
+      { "description": "Unknown role remains invalid", "data": { "role": "future" }, "valid": false },
+      {
+        "description": "Verbatim non-JSON function arguments",
+        "data": { "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": " { \"partial\": " }] },
+        "valid": true
+      },
+      {
+        "description": "Original empty string arguments",
+        "data": { "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": "" }] },
+        "valid": true
+      },
+      {
+        "description": "Object arguments remain valid",
+        "data": { "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": { "presentNull": null } }] },
+        "valid": true
+      },
+      {
+        "description": "Missing arguments remain absent",
+        "data": { "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f" }] },
+        "valid": true
+      },
+      {
+        "description": "Malformed known argument type remains invalid",
+        "data": { "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": false }] },
+        "valid": false
+      },
+      {
+        "description": "URI media type may be absent",
+        "data": { "role": "assistant", "contents": [{ "$type": "uri", "uri": "https://example.test/media" }] },
+        "valid": true
+      },
+      {
+        "description": "URI media type remains valid when supplied",
+        "data": { "role": "assistant", "contents": [{ "$type": "uri", "uri": "https://example.test/media", "mediaType": "image/png" }] },
+        "valid": true
+      },
+      {
+        "description": "URI media type must not be null",
+        "data": { "role": "assistant", "contents": [{ "$type": "uri", "uri": "https://example.test/media", "mediaType": null }] },
+        "valid": false
+      },
+      {
+        "description": "URI itself remains required",
+        "data": { "role": "assistant", "contents": [{ "$type": "uri" }] },
+        "valid": false
+      },
+      {
+        "description": "Complete unmodeled JSON including inert type names",
+        "data": { "role": "assistant", "contents": [{ "$type": "unknown", "content": { "$type": "future", "$runtimeType": "data-only", "metadata": { "null": null, "false": false, "empty": [] } } }] },
+        "valid": true
+      },
+      {
+        "description": "Explicit opaque null",
+        "data": { "role": "assistant", "contents": [{ "$type": "unknown", "content": null }] },
+        "valid": true
+      },
+      {
+        "description": "Explicit opaque scalar",
+        "data": { "role": "assistant", "contents": [{ "$type": "unknown", "content": "verbatim" }] },
+        "valid": true
+      },
+      {
+        "description": "Explicit opaque array",
+        "data": { "role": "assistant", "contents": [{ "$type": "unknown", "content": [0, false, null] }] },
+        "valid": true
+      },
+      {
+        "description": "Opaque wrapper must include original content",
+        "data": { "role": "assistant", "contents": [{ "$type": "unknown" }] },
+        "valid": false
+      },
+      {
+        "description": "Unwrapped unknown wire discriminator remains invalid",
+        "data": { "role": "assistant", "contents": [{ "$type": "future", "content": { "preserve": true } }] },
+        "valid": false
+      },
+      {
+        "description": "Known malformed text is not an opaque fallback",
+        "data": { "role": "assistant", "contents": [{ "$type": "text", "text": 0, "content": { "preserve": true } }] },
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "Named terminal structured value",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json#/$defs/terminalResponse" },
+    "tests": [
+      { "description": "Absent value", "data": { "messages": [] }, "valid": true },
+      { "description": "Present null", "data": { "messages": [], "value": null }, "valid": true },
+      { "description": "Present false", "data": { "messages": [], "value": false }, "valid": true },
+      { "description": "Present zero", "data": { "messages": [], "value": 0 }, "valid": true },
+      { "description": "Present empty string", "data": { "messages": [], "value": "" }, "valid": true },
+      { "description": "Present empty array", "data": { "messages": [], "value": [] }, "valid": true },
+      { "description": "Present empty object", "data": { "messages": [], "value": {} }, "valid": true },
+      { "description": "Nested JSON remains intact", "data": { "messages": [], "value": { "items": [null, false, 0, [], {}], "$runtimeType": "inert" } }, "valid": true },
+      { "description": "Value does not replace required messages", "data": { "value": false }, "valid": false }
+    ]
+  },
+  {
+    "description": "Legacy highest-seen ingestion scalar",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json#/$defs/data/properties/ingestedPositions" },
+    "tests": [
+      { "description": "Highest seen three does not encode gaps", "data": { "producer": 3 }, "valid": true },
+      { "description": "Zero remains valid", "data": { "producer": 0 }, "valid": true },
+      { "description": "Negative position remains invalid", "data": { "producer": -1 }, "valid": false },
+      { "description": "Receipt sets cannot masquerade as the legacy scalar", "data": { "producer": [1, 3] }, "valid": false }
+    ]
+  }
+]
diff --git a/schemas/tests/versioned-envelope-cases.json b/schemas/tests/versioned-envelope-cases.json
new file mode 100644
index 0000000..052d31a
--- /dev/null
+++ b/schemas/tests/versioned-envelope-cases.json
@@ -0,0 +1,252 @@
+[
+  {
+    "description": "Historical 1.0.0 full-envelope message boundary",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json" },
+    "tests": [
+      {
+        "description": "Original roles, object arguments and URI with media type remain valid",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": {} }, { "$type": "uri", "uri": "https://example.test/media", "mediaType": "image/png" }] }] }] } },
+        "valid": true
+      },
+      {
+        "description": "Developer role is not a historical correction",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "$type": "request", "messages": [{ "role": "developer" }] }] } },
+        "valid": false
+      },
+      {
+        "description": "String arguments are v2-only",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": " { \"partial\": " }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Empty string arguments are also v2-only",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": "" }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Omitted URI media type is v2-only even on a legacy error entry",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "$type": "errorResponse", "messages": [{ "role": "assistant", "contents": [{ "$type": "uri", "uri": "https://example.test/media" }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Historical explicit opaque object, scalar and null remain valid",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "unknown", "content": { "$type": "future", "$runtimeType": "inert", "metadata": [null, false, 0] } }, { "$type": "unknown", "content": "original" }, { "$type": "unknown", "content": null }] }] }] } },
+        "valid": true
+      },
+      {
+        "description": "Unwrapped unknown content discriminator remains invalid",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "future", "content": {} }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Malformed known fields remain invalid",
+        "data": { "schemaVersion": "1.0.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "text", "text": false }] }] }] } },
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "Historical 1.1.0 full-envelope message boundary",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json" },
+    "tests": [
+      {
+        "description": "Original roles, object arguments and URI with media type remain valid",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": {} }, { "$type": "uri", "uri": "https://example.test/media", "mediaType": "image/png" }] }] }] } },
+        "valid": true
+      },
+      {
+        "description": "Developer role is not a historical correction",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "$type": "request", "messages": [{ "role": "developer" }] }] } },
+        "valid": false
+      },
+      {
+        "description": "String arguments are v2-only",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": " { \"partial\": " }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Empty string arguments are also v2-only",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": "" }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Omitted URI media type is v2-only even on a legacy error entry",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "$type": "errorResponse", "messages": [{ "role": "assistant", "contents": [{ "$type": "uri", "uri": "https://example.test/media" }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Historical explicit opaque object, scalar and null remain valid",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "unknown", "content": { "$type": "future", "$runtimeType": "inert", "metadata": [null, false, 0] } }, { "$type": "unknown", "content": "original" }, { "$type": "unknown", "content": null }] }] }] } },
+        "valid": true
+      },
+      {
+        "description": "Unwrapped unknown content discriminator remains invalid",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "future", "content": {} }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Malformed known fields remain invalid",
+        "data": { "schemaVersion": "1.1.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "text", "text": false }] }] }] } },
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "Historical 1.2.0 full-envelope message boundary",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json" },
+    "tests": [
+      {
+        "description": "Original roles, object arguments and URI with media type remain valid",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": {} }, { "$type": "uri", "uri": "https://example.test/media", "mediaType": "image/png" }] }] }] } },
+        "valid": true
+      },
+      {
+        "description": "Developer role is not a historical correction",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "$type": "request", "messages": [{ "role": "developer" }] }] } },
+        "valid": false
+      },
+      {
+        "description": "String arguments are v2-only",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": " { \"partial\": " }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Empty string arguments are also v2-only",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": "" }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Omitted URI media type is v2-only even on a legacy error entry",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "$type": "errorResponse", "messages": [{ "role": "assistant", "contents": [{ "$type": "uri", "uri": "https://example.test/media" }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Historical explicit opaque object, scalar and null remain valid",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "unknown", "content": { "$type": "future", "$runtimeType": "inert", "metadata": [null, false, 0] } }, { "$type": "unknown", "content": "original" }, { "$type": "unknown", "content": null }] }] }] } },
+        "valid": true
+      },
+      {
+        "description": "Unwrapped unknown content discriminator remains invalid",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "future", "content": {} }] }] }] } },
+        "valid": false
+      },
+      {
+        "description": "Malformed known fields remain invalid",
+        "data": { "schemaVersion": "1.2.0", "data": { "conversationHistory": [{ "messages": [{ "role": "assistant", "contents": [{ "$type": "text", "text": false }] }] }] } },
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "Schema 2.0 full-envelope lossless message boundary",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json" },
+    "tests": [
+      {
+        "description": "Original object arguments and URI media type remain valid",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": {} }, { "$type": "uri", "uri": "https://example.test/media", "mediaType": "image/png" }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "Developer role in a v2 request",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "request", "messages": [{ "role": "developer" }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "String arguments in a v2 response",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": " { \"partial\": " }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "Empty string arguments in a v2 response",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "c", "name": "f", "arguments": "" }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "Omitted URI media type in a v2 error entry",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "errorResponse", "messages": [{ "role": "assistant", "contents": [{ "$type": "uri", "uri": "https://example.test/media" }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 compaction uses v2 messages without a correlation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "compaction", "messages": [{ "role": "developer", "contents": [{ "$type": "uri", "uri": "https://example.test/media" }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "V2 opaque mapping preserves the original JSON",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "unknown", "content": { "$type": "future", "$runtimeType": "inert", "metadata": [null, false, 0] } }, { "$type": "unknown", "content": "original" }, { "$type": "unknown", "content": null }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": true
+      },
+      {
+        "description": "Unwrapped unknown content discriminator remains invalid in v2",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "future", "content": {} }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "Malformed known fields remain invalid in v2",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "response", "messages": [{ "role": "assistant", "contents": [{ "$type": "text", "text": false }] }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "Unknown role remains invalid in v2",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [{ "$type": "request", "messages": [{ "role": "future" }] }], "terminalResults": {}, "completionReceipts": {} } },
+        "valid": false
+      },
+      {
+        "description": "V2 success payload independently uses expanded messages and structured value",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": { "c": { "correlationId": "c", "outcome": "succeeded", "completedAt": "2026-09-11T00:00:00Z", "response": { "messages": [{ "role": "developer", "contents": [{ "$type": "functionCall", "callId": "t", "name": "f", "arguments": " { \"partial\": " }, { "$type": "uri", "uri": "https://example.test/media" }, { "$type": "unknown", "content": { "$runtimeType": "inert", "metadata": null } }] }], "value": false } } }, "completionReceipts": { "c": { "correlationId": "c", "outcome": "succeeded", "completedAt": "2026-09-11T00:00:00Z", "resultState": "available" } } } },
+        "valid": true
+      },
+      {
+        "description": "V2 failure payload independently uses expanded messages",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": { "c": { "correlationId": "c", "outcome": "failed", "completedAt": "2026-09-11T00:00:00Z", "response": { "messages": [{ "role": "developer", "contents": [{ "$type": "uri", "uri": "https://example.test/media" }] }] }, "error": { "code": "example", "message": "Synthetic failure" } } }, "completionReceipts": { "c": { "correlationId": "c", "outcome": "failed", "completedAt": "2026-09-11T00:00:00Z", "resultState": "available" } } } },
+        "valid": true
+      },
+      {
+        "description": "V2 terminal messages still reject malformed known fields",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": { "c": { "correlationId": "c", "outcome": "succeeded", "completedAt": "2026-09-11T00:00:00Z", "response": { "messages": [{ "role": "assistant", "contents": [{ "$type": "functionCall", "callId": "t", "name": "f", "arguments": false }] }] } } }, "completionReceipts": { "c": { "correlationId": "c", "outcome": "succeeded", "completedAt": "2026-09-11T00:00:00Z", "resultState": "available" } } } },
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "Opaque runtime profiles and authoritative receipt outcomes",
+    "schema": { "$ref": "https://github.com/microsoft/agent-framework-durable-extension/schemas/durable-agent-entity-state.json" },
+    "tests": [
+      {
+        "description": "Nonconsumers preserve a separately versioned profile without interpreting owner fields",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": {}, "historyBinding": { "version": 99, "ownerKind": "runtime-specific", "future": [null, false, {}] } } },
+        "valid": true
+      },
+      {
+        "description": "Even malformed profile data passes shared shape validation, not relying-runtime validation",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": {}, "historyBinding": "opaque-unusable-profile" } },
+        "valid": true
+      },
+      {
+        "description": "Retained successful outcome survives payload expiry",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": { "c": { "correlationId": "c", "outcome": "succeeded", "completedAt": "2026-09-10T00:00:00Z", "resultState": "unavailable", "resultUnavailableAt": "2026-09-11T00:00:00Z" } } } },
+        "valid": true
+      },
+      {
+        "description": "Retained failed outcome survives payload expiry",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": { "c": { "correlationId": "c", "outcome": "failed", "completedAt": "2026-09-10T00:00:00Z", "resultState": "unavailable", "resultUnavailableAt": "2026-09-11T00:00:00Z" } } } },
+        "valid": true
+      },
+      {
+        "description": "Legacy receipt without outcome cannot be silently promoted to v2",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": { "c": { "correlationId": "c", "completedAt": "2026-09-10T00:00:00Z", "resultState": "unavailable", "resultUnavailableAt": "2026-09-11T00:00:00Z" } } } },
+        "valid": false
+      },
+      {
+        "description": "Null outcome is not authoritative success or failure",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": { "c": { "correlationId": "c", "outcome": null, "completedAt": "2026-09-10T00:00:00Z", "resultState": "unavailable", "resultUnavailableAt": "2026-09-11T00:00:00Z" } } } },
+        "valid": false
+      },
+      {
+        "description": "No synthetic unknown outcome is introduced into the v2 enum",
+        "data": { "schemaVersion": "2.0.0", "data": { "conversationHistory": [], "terminalResults": {}, "completionReceipts": { "c": { "correlationId": "c", "outcome": "unknown", "completedAt": "2026-09-10T00:00:00Z", "resultState": "unavailable", "resultUnavailableAt": "2026-09-11T00:00:00Z" } } } },
+        "valid": false
+      }
+    ]
+  }
+]