diff --git a/SCHEMA_INDEX.md b/SCHEMA_INDEX.md
index 8b2e4f2..67fbe74 100644
--- a/SCHEMA_INDEX.md
+++ b/SCHEMA_INDEX.md
@@ -4,8 +4,8 @@
 
 | Directory | Form | When to use |
 |-----------|------|-------------|
-| [`schema/`](./schema/) | **Unified** — one file per spec version validates the whole document. Files: `klickd-v1.json`, `klickd-v2.json`, `klickd-v3.4.schema.json`. | Single-pass validators, schema registries, third-party tooling. |
-| [`schemas/`](./schemas/) | **Split** — separate envelope and payload schemas for v3. Files: `klickd-envelope-v3.schema.json`, `klickd-payload-v3.schema.json`. | Secure decoders that validate the envelope *before* decryption and the payload *after*. |
+| [`schema/`](./schema/) | **Unified** — one file per spec version validates the whole document. Files: `klickd-v1.json`, `klickd-v2.json`, `klickd-v3.4.schema.json`, `klickd-v4-preview.schema.json` (preview), `klickd-v4.schema.json` (GA strict candidate). | Single-pass validators, schema registries, third-party tooling. |
+| [`schemas/`](./schemas/) | **Split** — separate envelope and payload schemas. Files: `klickd-envelope-v3.schema.json`, `klickd-payload-v3.schema.json`, `klickd-payload-v4-preview.schema.json` (preview), `klickd-payload-v4.schema.json` (GA strict candidate). | Secure decoders that validate the envelope *before* decryption and the payload *after*. |
 
 Both directories are **normative for v3.x (production, current and recommended)** and are kept in sync. The split form (`schemas/`) is the canonical pre-/post-decrypt boundary; the unified form (`schema/`) is the convenience form for single-shot validation.
 
@@ -30,7 +30,27 @@ In addition to the normative v3 schemas, the repository ships **permissive previ
 **These schemas are PERMISSIVE.** They use `additionalProperties: true` and only declare top-level hooks for the preview fields. They are intended to **accept and preserve** draft v4 structures, not to perform strict validation. They MUST NOT be used to reject a file that is otherwise a valid v3.5.1 file.
 
 - **Normative for production?** No. Production validation MUST use `schema/klickd-v3.4.schema.json` or the split v3 schemas under `schemas/`.
-- **Strict v4 validation?** Not in this preview. A future PR will introduce strict v4 schemas; until then, the preview schemas are deliberately loose.
+- **Strict v4 validation?** See the **v4 GA strict schemas** section below.
 - **Unknown fields?** A v4-preview reader MUST preserve unknown fields verbatim when round-tripping. See SPEC.md §33.7.
 
 See [SPEC.md §33](./SPEC.md) and the RFCs under [`docs/rfcs/`](./docs/rfcs/) for the design source.
+
+---
+
+## v4 GA strict schemas (P0-2 — coexist with preview, do NOT supersede it)
+
+To unblock the GA track described in [`docs/roadmap/ROAD-TO-V4-GA.md` §P0-2](./docs/roadmap/ROAD-TO-V4-GA.md), the repository now also ships **strict v4 schemas**. The preview schemas remain in place unchanged: both pairs coexist until the preview sunset is announced separately.
+
+| File | Form | Status | When to use |
+|------|------|--------|-------------|
+| [`schemas/klickd-payload-v4.schema.json`](./schemas/klickd-payload-v4.schema.json) | **Split — payload** | **GA strict candidate (normative target)** | Strict validation of a `.klickd` v4 decrypted payload: `verification_gates` (v1 core enum), `human_veto_policy`, `claim_sources` (v1), `media_profile` (RFC-001 v1, `version`+`entries[]`, hash strict), `migration` (RFC-004 v1 frozen fields), plus carry-over v3 surface. RFC-002 v2-additive fields (`reversibility`, `blast_radius`, `contract_tests`, `success_criteria`, `verification_artifacts`) remain permissive while Draft. |
+| [`schema/klickd-v4.schema.json`](./schema/klickd-v4.schema.json) | **Unified** | **GA strict candidate (normative target)** | Strict validation of a full v4 document. Encrypted files MUST carry `kdf` + `cipher` + `ciphertext` (envelope-v3 contract unchanged per §33.10 #2). |
+
+**Coexistence rules:**
+
+- Preview schemas (`*-v4-preview.schema.json`) remain authoritative for **preview** files (`preview: "v4.0.0-preview.1"`). They MUST continue to accept all preview vectors.
+- Strict schemas (`klickd-payload-v4.schema.json`, `klickd-v4.schema.json`) are the **GA strict target**. They accept both `payload_schema_version: "4.0"` (GA) and the legacy preview value `"4.0.0-preview.1"` so the 5 persona examples and preview vectors round-trip against them.
+- **Top-level `additionalProperties: true` is preserved.** SPEC.md §33.7 (unknown-field preservation) is unconditional and not relaxed by the strict schemas.
+- **No SDK is bumped.** No npm / PyPI / Zenodo release is triggered. No git tag is created.
+
+**Validation:** see [`scripts/validate_v4_schemas.py`](./scripts/validate_v4_schemas.py) for the canonical local validation runner.
diff --git a/docs/roadmap/ROAD-TO-V4-GA.md b/docs/roadmap/ROAD-TO-V4-GA.md
index 5342832..651912e 100644
--- a/docs/roadmap/ROAD-TO-V4-GA.md
+++ b/docs/roadmap/ROAD-TO-V4-GA.md
@@ -106,6 +106,19 @@ Chaque entrée précise : *Objet → Livrables → Critères de sortie (Definiti
   - validation passe sur tous les vectors v4 stricts ;
   - les vectors preview restent acceptés via le schéma preview (deux schémas coexistent jusqu’au sunset).
 - **Dépendances :** P0-1.
+- **Statut (2026-05-24) :** **GA candidate landed (docs/schema only, no SDK/release).** Le PR P0-2 introduit
+  [`schemas/klickd-payload-v4.schema.json`](../../schemas/klickd-payload-v4.schema.json) et
+  [`schema/klickd-v4.schema.json`](../../schema/klickd-v4.schema.json) (strict sur les sections RFC-001 v1
+  `Accepted` et RFC-002 v1 core `Accepted` ; permissif sur les sections RFC-002 v2-additive et RFC-004 encore
+  en `Draft`). `additionalProperties: true` est conservé **au niveau racine** pour respecter le contrat de
+  préservation des champs inconnus de [SPEC.md §33.7](../../SPEC.md). Les 5 personas de
+  [`examples/v4/personas/`](../../examples/v4/personas/) et tous les `expected_payload` de
+  [`tests/vectors_v40_preview.json`](../../tests/vectors_v40_preview.json) valident contre le schéma strict.
+  Les schémas preview restent en place inchangés (coexistence, pas de remplacement). **Aucun bump de version
+  SDK, aucun tag, aucune release npm/PyPI/Zenodo.** Le runner local est
+  [`scripts/validate_v4_schemas.py`](../../scripts/validate_v4_schemas.py). Les vectors v4 *stricts*
+  (P0-6) restent à produire avant de pouvoir cocher la DoD complète ; à ce stade la DoD est validée sur le
+  corpus preview existant et les 5 personas.
 
 #### P0-3 — SDK Python `klickd` 4.0.0
 
diff --git a/examples/v4/personas/README.md b/examples/v4/personas/README.md
index ea999f2..5eb57e9 100644
--- a/examples/v4/personas/README.md
+++ b/examples/v4/personas/README.md
@@ -123,10 +123,12 @@ forte sur les sections preview).
 - [x] Passphrase de test publique documentée (`klickd-example-only`), sans
       jamais figurer comme contenu chiffré.
 - [x] Validation contre le schéma preview permissif (cf. §5 ci-dessous).
-- [ ] Validation stricte v4 ([P0-2 / P0-6](../../../docs/roadmap/ROAD-TO-V4-GA.md)) :
-      **différée**. Le schéma strict v4 et les vectors stricts v4 n'existent
-      pas encore — la DoD complète sera atteignable une fois P0-2/P0-6 mergés,
-      conformément à l'ordre des dépendances inscrit dans ROAD-TO-V4-GA.
+- [x] Validation stricte v4 contre [`schemas/klickd-payload-v4.schema.json`](../../../schemas/klickd-payload-v4.schema.json)
+      (P0-2 GA candidate, livré séparément). Les 5 personas valident sans erreur —
+      voir [`scripts/validate_v4_schemas.py`](../../../scripts/validate_v4_schemas.py).
+- [ ] Validation contre les vectors v4 *stricts*
+      ([P0-6](../../../docs/roadmap/ROAD-TO-V4-GA.md)) :
+      **différée**. Les vectors v4 stricts n'existent pas encore — track P0-6.
 
 ### Reproduire la validation locale
 
diff --git a/schema/README.md b/schema/README.md
index d731650..9f1734d 100644
--- a/schema/README.md
+++ b/schema/README.md
@@ -8,6 +8,7 @@ This directory contains **unified** JSON Schemas — each file validates a compl
 | `klickd-v2.json` | v2.x | PBKDF2-SHA256 + 4-field AAD. |
 | `klickd-v3.4.schema.json` | v3.4 (current) | Argon2id + RFC 8785 JCS AAD + `kdf`/`cipher` blocks. Forward-compatible with v3.5 fields. |
 | `klickd-v4-preview.schema.json` | **v4.0.0-preview.1 (PREVIEW, non-normative, NOT GA)** | Permissive (`additionalProperties: true`) acceptance schema for draft v4 documents with top-level hooks for `media_profile` / `verification_gates` / `human_veto_policy` / `claim_sources` / `verification_artifacts` / `migration` / `context_cost` / `profile_kind`. See SPEC.md §33. |
+| `klickd-v4.schema.json` | **v4 GA strict candidate (P0-2)** | Strict unified schema. Encrypted v4 files MUST carry `kdf` + `cipher` + `ciphertext` (envelope-v3 contract unchanged per §33.10 #2). Inline payload fields cross-reference `../schemas/klickd-payload-v4.schema.json`. Top-level `additionalProperties: true` preserved (SPEC.md §33.7). Coexists with the preview schema — does NOT supersede it. |
 
 **Use these files** when a single-schema validation is sufficient (CI tooling, third-party integrations, schema registries).
 
diff --git a/schema/klickd-v4.schema.json b/schema/klickd-v4.schema.json
new file mode 100644
index 0000000..824557c
--- /dev/null
+++ b/schema/klickd-v4.schema.json
@@ -0,0 +1,129 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://klickd.app/schema/v4/klickd.schema.json",
+  "title": "klickd v4 — Unified (Strict GA candidate, normative)",
+  "description": "Strict unified JSON Schema for a .klickd v4 document (envelope + optional inline payload). This schema is the GA strict equivalent of the permissive klickd-v4-preview.schema.json. It validates the envelope shape strictly (mirroring the v3 envelope contract — Argon2id + AES-256-GCM is unchanged in v4 per SPEC.md §33.10 #2) and, for unencrypted files, validates the inline payload against the strict v4 payload schema (klickd-payload-v4.schema.json). Top-level additionalProperties is TRUE to preserve unknown fields verbatim (SPEC.md §33.7 forward-compatibility invariant). Does NOT supersede the permissive preview schema (klickd-v4-preview.schema.json) — both coexist.",
+  "type": "object",
+  "additionalProperties": true,
+  "required": ["klickd_version", "created_at", "encrypted"],
+  "properties": {
+    "klickd_version": {
+      "type": "string",
+      "description": "Wire / envelope version. Strict v4 GA producers SHOULD emit '4.0'. v3.x values are also accepted because the v3 envelope contract is unchanged (§33.10 #2) and a v3.x file remains readable by a v4 reader.",
+      "pattern": "^(3|4)\\.\\d+(\\.[0-9A-Za-z-.]+)?$"
+    },
+    "preview": {
+      "type": "string",
+      "description": "OPTIONAL preview marker. Absent on GA strict files. If present, this file was written against a preview iteration (e.g. 'v4.0.0-preview.1')."
+    },
+    "created_at": {
+      "type": "string",
+      "description": "RFC 3339 UTC timestamp of file creation. Z-suffix only, no fractional seconds (matches v3 envelope strict contract).",
+      "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z$"
+    },
+    "encrypted": {
+      "type": "boolean"
+    },
+    "domain": {
+      "type": "string",
+      "minLength": 1,
+      "description": "Semantic category. Registered values follow v3 (education, work, finance, legal, creative, health, research, robotics, gaming, creator). Custom non-empty strings are permitted."
+    },
+    "profile_kind": {
+      "type": "string",
+      "description": "Top-level discriminator for the profile shape. Reserved canonical values: 'learner', 'agent', 'team', 'robot', 'creator'."
+    },
+    "domain_schema_version": {
+      "type": "string",
+      "pattern": "^([a-z][a-z0-9_-]*-\\d+\\.\\d+|\\d+\\.\\d+(\\.\\d+)?)$"
+    },
+    "kdf": {
+      "type": "object",
+      "description": "Structured KDF block — same contract as envelope-v3 §15.",
+      "required": ["name", "params", "salt"],
+      "additionalProperties": false,
+      "properties": {
+        "name": {"type": "string", "enum": ["argon2id", "pbkdf2-sha256"]},
+        "params": {
+          "oneOf": [
+            {
+              "type": "object",
+              "required": ["m", "t", "p"],
+              "additionalProperties": false,
+              "properties": {
+                "m": {"type": "integer", "minimum": 65536},
+                "t": {"type": "integer", "minimum": 1},
+                "p": {"type": "integer", "minimum": 1}
+              }
+            },
+            {
+              "type": "object",
+              "required": ["iterations"],
+              "additionalProperties": false,
+              "properties": {
+                "iterations": {"type": "integer", "minimum": 600000}
+              }
+            }
+          ]
+        },
+        "salt": {"type": "string"}
+      }
+    },
+    "cipher": {
+      "type": "object",
+      "description": "Structured cipher block — same contract as envelope-v3 §16. v4 does not introduce a new cipher.",
+      "required": ["name", "iv"],
+      "additionalProperties": false,
+      "properties": {
+        "name": {"type": "string", "const": "AES-256-GCM"},
+        "iv": {"type": "string"}
+      }
+    },
+    "ciphertext": {
+      "type": "string",
+      "description": "AES-256-GCM ciphertext (base64 padded). Required when encrypted=true."
+    },
+    "iv": {
+      "type": "string",
+      "description": "Legacy top-level IV mirror, retained for v3.0 round-trip parity. New producers SHOULD place IV inside the structured cipher block."
+    },
+    "kdf_salt": {
+      "type": "string",
+      "description": "Legacy top-level salt mirror, retained for v3.0 round-trip parity."
+    },
+    "payload_schema_version": {
+      "type": "string",
+      "description": "Payload schema version when the payload is inline (encrypted=false). Strict v4 GA value: '4.0'. Preview '4.0.0-preview.1' accepted for round-trip.",
+      "enum": ["4.0", "4.0.0-preview.1"]
+    },
+    "media_profile": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/media_profile"},
+    "verification_gates": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/verification_gates"},
+    "human_veto_policy": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/human_veto_policy"},
+    "claim_sources": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/claim_sources"},
+    "verification_artifacts": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/verification_artifacts"},
+    "contract_tests": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/contract_tests"},
+    "success_criteria": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/success_criteria"},
+    "reversibility": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/reversibility"},
+    "blast_radius": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/blast_radius"},
+    "risk_thresholds": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/risk_thresholds"},
+    "preflight_checks": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/preflight_checks"},
+    "error_journal": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/error_journal"},
+    "migration": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/migration"},
+    "context_cost": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/context_cost"},
+    "gaming_profile": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/gaming_profile"},
+    "deprecated_fields": {"$ref": "https://klickd.app/schemas/v4/klickd-payload.schema.json#/properties/deprecated_fields"}
+  },
+  "allOf": [
+    {
+      "if": {
+        "type": "object",
+        "properties": {"encrypted": {"const": true}},
+        "required": ["encrypted"]
+      },
+      "then": {
+        "required": ["kdf", "cipher", "ciphertext"],
+        "description": "Encrypted v4 file MUST carry kdf + cipher + ciphertext (envelope-v3 contract retained)."
+      }
+    }
+  ]
+}
diff --git a/schemas/README.md b/schemas/README.md
index 7d4b316..f637f9f 100644
--- a/schemas/README.md
+++ b/schemas/README.md
@@ -7,6 +7,7 @@ This directory contains the **split** JSON Schemas for `.klickd` v3:
 | `klickd-envelope-v3.schema.json` | Outer JSON envelope (encrypted). Validates `klickd_version`, `kdf`, `cipher`, `ciphertext`, AAD-relevant fields. |
 | `klickd-payload-v3.schema.json` | Inner decrypted payload. Validates `identity`, `agent_instructions`, `user_preferences`, `context`, `knowledge`, `memory`, etc. |
 | `klickd-payload-v4-preview.schema.json` | **v4.0.0-preview.1 payload (PREVIEW, non-normative, NOT GA).** Permissive (`additionalProperties: true`) acceptance schema for draft v4 payloads with top-level hooks for `media_profile` / `verification_gates` / `human_veto_policy` / `claim_sources` / `verification_artifacts` / `migration` / `context_cost` / `profile_kind`. See SPEC.md §33. |
+| `klickd-payload-v4.schema.json` | **v4 GA strict candidate (P0-2).** Strict payload schema: `verification_gates` (v1 enum), `human_veto_policy`, `claim_sources` (v1), `media_profile` (RFC-001 v1, `version`+`entries[]`, BLAKE3 hash strict), `migration` (RFC-004 v1 frozen fields). RFC-002 v2-additive fields (`reversibility`, `blast_radius`, `contract_tests`, `success_criteria`, `verification_artifacts`) remain permissive while Draft. Top-level `additionalProperties: true` preserved (SPEC.md §33.7). Coexists with the preview schema — does NOT supersede it. |
 
 **Use this split form** when you need to validate the envelope *before* decryption and the payload *after* decryption as two independent steps (typical of secure decoders that fail-fast on the envelope).
 
diff --git a/schemas/klickd-payload-v4.schema.json b/schemas/klickd-payload-v4.schema.json
new file mode 100644
index 0000000..89b2f42
--- /dev/null
+++ b/schemas/klickd-payload-v4.schema.json
@@ -0,0 +1,354 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://klickd.app/schemas/v4/klickd-payload.schema.json",
+  "title": "klickd Payload v4 (Strict GA candidate, normative)",
+  "description": "Strict JSON Schema for the .klickd v4 inner payload. This schema is the GA strict equivalent of the permissive klickd-payload-v4-preview.schema.json. Strict blocks correspond to RFC-001 (media_profile v1, Accepted) and RFC-002 v1 core (verification_gates, human_veto_policy, claim_sources v1, Accepted). Sections that remain Draft (RFC-002 v2-additive: contract_tests, success_criteria, reversibility, blast_radius, verification_artifacts, error_journal.rule_created; RFC-004 migration runtime) are accepted but left permissive so they can be tightened by a future strict schema bump without breaking GA writers. Top-level additionalProperties is TRUE to preserve unknown fields verbatim (SPEC.md §33.7 forward-compatibility invariant). Strict shape on frozen sub-objects uses additionalProperties: false locally. Does NOT supersede the permissive preview schema (klickd-payload-v4-preview.schema.json) — both coexist until the preview sunset announced separately.",
+  "type": "object",
+  "required": [
+    "payload_schema_version"
+  ],
+  "additionalProperties": true,
+  "properties": {
+    "payload_schema_version": {
+      "type": "string",
+      "description": "Payload schema version. For GA strict files, the canonical value is '4.0'. The preview value '4.0.0-preview.1' is also accepted so a preview file already in the wild round-trips against the strict schema without forcing a rewrite. A future strict bump (4.1, etc.) MAY tighten this enum.",
+      "enum": ["4.0", "4.0.0-preview.1"]
+    },
+    "domain_schema_version": {
+      "type": "string",
+      "description": "Domain-specific schema version. Two accepted forms: (a) v3-style '{domain}-{major}.{minor}' (e.g. 'education-1.2'); (b) bare semver-ish '{major}.{minor}(.{patch})?' for domain-agnostic profiles (e.g. '1.0.0').",
+      "pattern": "^([a-z][a-z0-9_-]*-\\d+\\.\\d+|\\d+\\.\\d+(\\.\\d+)?)$"
+    },
+    "preview": {
+      "type": "string",
+      "description": "OPTIONAL preview marker. Present only on files written against a preview iteration (e.g. 'v4.0.0-preview.1'). Absent on GA strict files."
+    },
+    "profile_kind": {
+      "type": "string",
+      "description": "Top-level discriminator for the profile shape. Reserved canonical values: 'learner', 'agent', 'team', 'robot', 'creator'. Custom strings are permitted (extension space). v3.x is implicitly 'learner'."
+    },
+    "injection_target": {
+      "type": "string",
+      "enum": ["system_prompt", "user_message", "both"],
+      "description": "Where to inject the .klickd context (carried over from v3.x §20.2)."
+    },
+    "identity": {
+      "type": "object",
+      "description": "Persistent user identity attributes. Carried over from v3 SPEC §8; same strictness as v3 payload schema. All sub-fields are OPTIONAL.",
+      "additionalProperties": true,
+      "properties": {
+        "name": {"type": "string", "maxLength": 256},
+        "display_name": {"type": "string", "maxLength": 256, "description": "v4 GA preferred user-facing alias. Either 'name' or 'display_name' may be used; producers SHOULD pick one."},
+        "language": {"type": "string", "description": "BCP 47 language tag."},
+        "timezone": {"type": "string", "description": "IANA time zone identifier."},
+        "communication_style": {"type": "string"}
+      }
+    },
+    "companion_identity": {
+      "type": "object",
+      "description": "Optional companion / co-agent persona. Same surface as v3.4 §27. Permissive.",
+      "additionalProperties": true
+    },
+    "context": {
+      "type": "object",
+      "description": "Operational session state. Carried over from v3 SPEC §9. Permissive (unevaluatedProperties policy of v3 retained).",
+      "additionalProperties": true
+    },
+    "knowledge": {
+      "type": "object",
+      "description": "Structured knowledge state. Carried over from v3 SPEC §10. Permissive.",
+      "additionalProperties": true
+    },
+    "memory": {
+      "type": "array",
+      "maxItems": 1000,
+      "description": "Structured conversation/event log. Same v3 §11 constraints retained.",
+      "items": {"type": "object", "additionalProperties": true}
+    },
+    "learning_goal": {
+      "type": "object",
+      "description": "User's stated learning / delivery goal. Same surface as v3 §27. Permissive.",
+      "additionalProperties": true,
+      "properties": {
+        "type": {"type": "string"},
+        "deadline": {"type": "string"},
+        "stakes": {"type": "string", "enum": ["low", "medium", "high"]}
+      }
+    },
+    "user_preferences": {
+      "oneOf": [
+        {"type": "string", "maxLength": 32768},
+        {"type": "object", "additionalProperties": true}
+      ],
+      "description": "Canonical type is string (v3.5 §22.6). Object form retained for backward compatibility."
+    },
+    "agent_instructions": {
+      "type": "string",
+      "maxLength": 32768,
+      "description": "System-prompt injection string. Same v3 §7.2 contract."
+    },
+    "onboarding_trigger": {
+      "type": "string",
+      "description": "Optional onboarding trigger (v3.4 §29b). Common values: 'on_new_agent', 'manual'."
+    },
+    "ethics": {
+      "type": "object",
+      "description": "Ethical guard surface (v3.x). Permissive in this schema; safety / locked fields are governed by docs/spec/DEPRECATION_POLICY_V4.md §9.",
+      "additionalProperties": true
+    },
+    "media_profile": {
+      "description": "RFC-001 v1 (Accepted): portable, hash-referenced media context. Strict on the v1 frozen surface (versioned + entries[]); a permissive 'summary' form (preview-era) is also accepted for round-trip compatibility. New modalities / fields land via additive RFC bumps.",
+      "oneOf": [
+        {
+          "type": "object",
+          "additionalProperties": false,
+          "required": ["version", "entries"],
+          "properties": {
+            "version": {"type": "integer", "const": 1, "description": "media_profile schema version. v1 per RFC-001."},
+            "entries": {
+              "type": "array",
+              "maxItems": 256,
+              "items": {"$ref": "#/$defs/mediaProfileEntry"}
+            }
+          }
+        },
+        {
+          "type": "object",
+          "description": "Permissive summary form (preview-era). Strict producers SHOULD migrate to the versioned + entries[] form. Kept for round-trip parity with vectors_v40_preview.json.",
+          "additionalProperties": true,
+          "not": {"required": ["version", "entries"]}
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "verification_gates": {
+      "description": "RFC-002 v1 core (Accepted): user's preferred friction profile per action class. Two accepted shapes: (a) structured form (recommended) with version + gates[]; (b) flat map {action_class: level} for compactness (used by §33.5 minimal example and preview readers).",
+      "oneOf": [
+        {
+          "type": "object",
+          "additionalProperties": false,
+          "required": ["version", "gates"],
+          "properties": {
+            "version": {"type": "integer", "const": 1},
+            "user_default": {"$ref": "#/$defs/gateLevel"},
+            "gates": {
+              "type": "array",
+              "maxItems": 256,
+              "items": {"$ref": "#/$defs/gateEntry"}
+            }
+          }
+        },
+        {
+          "type": "object",
+          "description": "Flat map form: {action_class: gate_level}. Each value MUST be one of the five canonical levels.",
+          "additionalProperties": {"$ref": "#/$defs/gateLevel"}
+        }
+      ]
+    },
+    "human_veto_policy": {
+      "description": "RFC-002 v1 (Accepted): standing rules about when a human MUST be in the loop. Overrides any lower gate.",
+      "type": ["object", "null"],
+      "additionalProperties": false,
+      "properties": {
+        "applies_to": {
+          "type": "array",
+          "items": {"type": "string"},
+          "maxItems": 64,
+          "description": "List of action classes for which a human veto is required."
+        },
+        "second_party": {
+          "type": ["string", "null"],
+          "description": "Optional named second party who may unlock. null means owner-only."
+        },
+        "min_level": {
+          "$ref": "#/$defs/gateLevel",
+          "description": "Floor gate level. The policy MUST NOT resolve below this level for any action class in 'applies_to'. RFC-002 v1 §4 #6 — human veto is sacred."
+        },
+        "rationale": {"type": "string", "maxLength": 1024}
+      }
+    },
+    "claim_sources": {
+      "description": "RFC-002 v1 (Accepted) + v2-additive (Draft). Strict on v1 fields ('prefer', 'require_citation_for'); 'records' and extended fields remain permissive (v2 still Draft).",
+      "type": ["object", "null"],
+      "additionalProperties": true,
+      "properties": {
+        "prefer": {
+          "type": "array",
+          "items": {"type": "string"},
+          "maxItems": 64,
+          "description": "Ordered preference list. Each entry is a free-form source identifier; common values: 'user_supplied', 'tool:web_search', 'tool:doi_resolver'."
+        },
+        "require_citation_for": {
+          "type": "array",
+          "items": {"type": "string"},
+          "maxItems": 64
+        },
+        "records": {
+          "type": "array",
+          "description": "v2-additive (Draft). Permissive until promoted.",
+          "items": {"type": "object", "additionalProperties": true}
+        }
+      }
+    },
+    "risk_thresholds": {
+      "description": "RFC-002 v1 (Accepted): numeric / categorical knobs. Permissive on inner shape — extension space.",
+      "type": ["object", "null"],
+      "additionalProperties": true
+    },
+    "preflight_checks": {
+      "description": "RFC-002 v1 (Accepted): small named checks to run before acting. Each entry is an object with at minimum 'name'.",
+      "type": ["array", "null"],
+      "items": {"type": ["object", "string"], "additionalProperties": true}
+    },
+    "error_journal": {
+      "description": "RFC-002 v1 (Accepted): append-only lessons learned. Permissive on entry shape ('rule_created' remains Draft in v2-additive).",
+      "type": ["array", "null"],
+      "items": {"type": "object", "additionalProperties": true}
+    },
+    "verification_artifacts": {
+      "description": "RFC-002 §8b.8 (Draft, v2-additive). Permissive: pointer ledger, not a payload sink. Accepted as null or array.",
+      "type": ["array", "null"],
+      "items": {"type": "object", "additionalProperties": true}
+    },
+    "contract_tests": {
+      "description": "RFC-002 v2-additive (Draft). Permissive.",
+      "type": ["array", "null"],
+      "items": {"type": "object", "additionalProperties": true}
+    },
+    "success_criteria": {
+      "description": "RFC-002 v2-additive (Draft). Permissive.",
+      "type": ["object", "array", "null"],
+      "additionalProperties": true
+    },
+    "reversibility": {
+      "description": "RFC-002 v2-additive (Draft). Permissive — typical shape is {action_class: enum<reversible|costly_to_reverse|irreversible|low|none|high>} but enums are not yet frozen.",
+      "type": ["object", "null"],
+      "additionalProperties": true
+    },
+    "blast_radius": {
+      "description": "RFC-002 v2-additive (Draft). Permissive.",
+      "type": ["object", "null"],
+      "additionalProperties": true
+    },
+    "migration": {
+      "description": "RFC-004 (Draft): optional migration metadata block. Audit-only — no migration tooling ships with the strict schema. Strict on v1 frozen fields; extension fields permitted.",
+      "type": ["object", "null"],
+      "additionalProperties": true,
+      "properties": {
+        "source_version": {"type": "string"},
+        "migrated_at": {
+          "type": "string",
+          "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(\\.\\d+)?Z$"
+        },
+        "migration_report_ref": {"type": "string"},
+        "backup_ref": {"type": "string"}
+      }
+    },
+    "context_cost": {
+      "description": "Research/benchmark track (benchmarks/context_cost/RFC.md). No spec semantics depend on this field. Permissive.",
+      "type": ["object", "null"],
+      "additionalProperties": true
+    },
+    "gaming_profile": {
+      "description": "R4-P1-4 gaming.klickd baseline (preview, registry-based). NOT a v4 MUST. Accepted as a registry-defined optional profile; permissive structure.",
+      "type": ["object", "null"],
+      "additionalProperties": true
+    },
+    "deprecated_fields": {
+      "description": "OPTIONAL informational block defined by docs/spec/DEPRECATION_POLICY_V4.md §6. Lists fields the producer has emitted as 'deprecated' status. Readers that don't understand it MUST silently ignore (§33.7).",
+      "type": ["array", "null"],
+      "items": {
+        "type": "object",
+        "additionalProperties": true,
+        "required": ["name"],
+        "properties": {
+          "name": {"type": "string"},
+          "since": {"type": "string"},
+          "replacement": {"type": ["string", "null"]},
+          "removal_target": {"type": ["string", "null"]}
+        }
+      }
+    },
+    "_example_metadata": {
+      "description": "Optional non-normative block used by repository examples (see examples/v4/personas/README.md). Carries 'persona', 'non_normative', 'contains_real_pii', 'contains_secrets', etc. A reader MUST NOT use this block as a trust signal.",
+      "type": "object",
+      "additionalProperties": true
+    }
+  },
+  "$defs": {
+    "gateLevel": {
+      "type": "string",
+      "enum": ["silent", "warn", "confirm", "block", "require-owner"],
+      "description": "RFC-002 v1 §6 — fixed enum of five gate levels. No new levels are added in GA."
+    },
+    "gateEntry": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["action_class", "level"],
+      "properties": {
+        "id": {"type": "string", "maxLength": 128},
+        "action_class": {"type": "string", "maxLength": 128},
+        "level": {"$ref": "#/$defs/gateLevel"},
+        "reason": {"type": "string", "maxLength": 1024}
+      }
+    },
+    "mediaProfileEntry": {
+      "type": "object",
+      "additionalProperties": true,
+      "required": ["id", "modality", "hash"],
+      "description": "RFC-001 v1 entry. Strict on v1 frozen fields (id, modality, hash). Additional metadata (consent, producer, etc.) is permitted as extension surface.",
+      "properties": {
+        "id": {"type": "string", "maxLength": 128},
+        "modality": {
+          "type": "string",
+          "enum": ["voice", "image", "document", "embedding"],
+          "description": "RFC-001 v1 §4 #3 — closed enum at v1. Custom modalities live under 'x_*' namespaces (outside this entry)."
+        },
+        "label": {"type": "string", "maxLength": 256},
+        "language": {"type": "string"},
+        "uri": {"type": "string", "description": "May be file://, https://, ipfs://, cas://<hash>, or a relative path. Reader chooses how to resolve."},
+        "media_type": {"type": "string"},
+        "byte_size": {"type": "integer", "minimum": 0},
+        "duration_ms": {"type": "integer", "minimum": 0},
+        "bytes_b64": {
+          "type": "string",
+          "contentEncoding": "base64",
+          "description": "Inline base64 PERMITTED ONLY for entries ≤ 16 KiB total (RFC-001 v1 §4 #1). Strict enforcement of the 16 KiB cap is not expressible in JSON Schema and is enforced by reader-side logic."
+        },
+        "hash": {
+          "type": "object",
+          "additionalProperties": false,
+          "required": ["algo", "value"],
+          "properties": {
+            "algo": {"type": "string", "const": "blake3", "description": "RFC-001 v1 §4 #2 — one hash, one algorithm: BLAKE3."},
+            "value": {"type": "string", "description": "Hash value, encoding per RFC-001 (base64 or hex-prefixed). Strict format enforcement is reader-side."}
+          }
+        },
+        "producer": {
+          "type": "object",
+          "additionalProperties": true,
+          "properties": {
+            "kind": {"type": "string"},
+            "device": {"type": "string"}
+          }
+        },
+        "consent": {
+          "type": "object",
+          "additionalProperties": true,
+          "description": "RFC-001 v1 §4 #5 — consent is per-entry, not per-file.",
+          "properties": {
+            "purposes": {
+              "type": "array",
+              "items": {"type": "string"},
+              "maxItems": 64
+            },
+            "expires_at": {"type": "string"},
+            "revocable": {"type": "boolean"}
+          }
+        }
+      }
+    }
+  }
+}
diff --git a/scripts/validate_v4_schemas.py b/scripts/validate_v4_schemas.py
new file mode 100755
index 0000000..a58b8ee
--- /dev/null
+++ b/scripts/validate_v4_schemas.py
@@ -0,0 +1,163 @@
+#!/usr/bin/env python3
+"""
+P0-2 strict v4 schema validation runner.
+
+Validates the .klickd v4 GA strict candidate schemas against:
+  - the 5 persona examples under examples/v4/personas/
+  - examples/v4-preview/minimal.klickd (unified shape only — it carries no
+    payload_schema_version on purpose)
+  - every expected_payload of tests/vectors_v40_preview.json (payload schema)
+  - a fixed set of negative cases (each one MUST fail validation)
+
+Exits 0 on success, 1 on any unexpected error. Intended for local use and
+as a candidate CI step. Does not modify any file. No SDK is bumped, no
+release is triggered. See docs/roadmap/ROAD-TO-V4-GA.md §P0-2.
+"""
+from __future__ import annotations
+
+import json
+import pathlib
+import sys
+
+try:
+    from jsonschema import Draft202012Validator, RefResolver
+except ImportError:
+    print("ERROR: jsonschema not installed. pip install jsonschema", file=sys.stderr)
+    sys.exit(2)
+
+REPO = pathlib.Path(__file__).resolve().parent.parent
+PAYLOAD_SCHEMA_PATH = REPO / "schemas" / "klickd-payload-v4.schema.json"
+UNIFIED_SCHEMA_PATH = REPO / "schema" / "klickd-v4.schema.json"
+
+
+def load_validators() -> tuple[Draft202012Validator, Draft202012Validator]:
+    payload_schema = json.loads(PAYLOAD_SCHEMA_PATH.read_text())
+    unified_schema = json.loads(UNIFIED_SCHEMA_PATH.read_text())
+    store = {
+        payload_schema["$id"]: payload_schema,
+        unified_schema["$id"]: unified_schema,
+    }
+    resolver = RefResolver.from_schema(unified_schema, store=store)
+    return (
+        Draft202012Validator(payload_schema),
+        Draft202012Validator(unified_schema, resolver=resolver),
+    )
+
+
+def report(label: str, errs: list, expect_fail: bool = False) -> int:
+    ok = bool(errs) if expect_fail else not errs
+    tag = "OK" if ok else "FAIL"
+    print(f"[{tag}] {label} — errors={len(errs)}")
+    for e in errs[:3]:
+        print(f"       - {list(e.path)}: {e.message[:200]}")
+    return 0 if ok else 1
+
+
+def main() -> int:
+    payload_validator, unified_validator = load_validators()
+    failures = 0
+
+    # 1. 5 persona examples — unified + payload validation
+    for p in sorted((REPO / "examples" / "v4" / "personas").glob("*.klickd")):
+        data = json.loads(p.read_text())
+        failures += report(
+            f"persona unified {p.name}",
+            list(unified_validator.iter_errors(data)),
+        )
+        failures += report(
+            f"persona payload  {p.name}",
+            list(payload_validator.iter_errors(data)),
+        )
+
+    # 2. SPEC §33.5 minimal preview example — unified validation only
+    #    (no payload_schema_version; it's an envelope-shaped illustration).
+    minimal = REPO / "examples" / "v4-preview" / "minimal.klickd"
+    if minimal.is_file():
+        failures += report(
+            f"unified {minimal.relative_to(REPO)}",
+            list(unified_validator.iter_errors(json.loads(minimal.read_text()))),
+        )
+
+    # 3. Every expected_payload in vectors_v40_preview.json — payload schema
+    vectors = REPO / "tests" / "vectors_v40_preview.json"
+    if vectors.is_file():
+        vdoc = json.loads(vectors.read_text())
+        for v in vdoc.get("vectors", []):
+            ep = v.get("expected_payload")
+            if not ep:
+                continue
+            failures += report(
+                f"vector  {v['id']}",
+                list(payload_validator.iter_errors(ep)),
+            )
+
+    # 4. Negative cases — each MUST fail.
+    negatives = [
+        (
+            "neg: unknown gate level",
+            payload_validator,
+            {
+                "payload_schema_version": "4.0",
+                "verification_gates": {
+                    "version": 1,
+                    "gates": [{"action_class": "x", "level": "loud"}],
+                },
+            },
+        ),
+        (
+            "neg: media entry missing hash",
+            payload_validator,
+            {
+                "payload_schema_version": "4.0",
+                "media_profile": {
+                    "version": 1,
+                    "entries": [{"id": "x", "modality": "voice"}],
+                },
+            },
+        ),
+        (
+            "neg: unsupported payload_schema_version",
+            payload_validator,
+            {"payload_schema_version": "9.9"},
+        ),
+        (
+            "neg: encrypted=true missing kdf/cipher/ciphertext",
+            unified_validator,
+            {
+                "klickd_version": "4.0",
+                "created_at": "2026-05-24T00:00:00Z",
+                "encrypted": True,
+            },
+        ),
+        (
+            "neg: media modality not in v1 enum",
+            payload_validator,
+            {
+                "payload_schema_version": "4.0",
+                "media_profile": {
+                    "version": 1,
+                    "entries": [
+                        {
+                            "id": "x",
+                            "modality": "video",
+                            "hash": {"algo": "blake3", "value": "xx"},
+                        }
+                    ],
+                },
+            },
+        ),
+    ]
+    for label, validator, data in negatives:
+        failures += report(
+            label, list(validator.iter_errors(data)), expect_fail=True
+        )
+
+    if failures:
+        print(f"\nFAILED: {failures} validation issue(s).", file=sys.stderr)
+        return 1
+    print("\nAll v4 strict-schema validations passed.")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())