diff --git a/README.md b/README.md
index 6c17688..9900bf3 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ A minimal vBRIEF document has just four fields:
 
 ```json
 {
-  "vBRIEFInfo": { "version": "0.5" },
+  "vBRIEFInfo": { "version": "0.7" },
   "plan": {
     "title": "My First Plan",
     "status": "running",
@@ -47,12 +47,12 @@ Start simple. Add structure only when you need it.
 
 | Document | Description |
 |----------|-------------|
-| [docs/vbrief-spec-0.5.md](docs/vbrief-spec-0.5.md) | Formal specification (RFC 2119) |
+| [docs/vbrief-spec-0.7.md](docs/vbrief-spec-0.7.md) | Formal specification v0.7 (RFC 2119) |
 | [docs/GUIDE.md](docs/GUIDE.md) | Reference guide with patterns and recipes |
 | [docs/getting-started.md](docs/getting-started.md) | Tutorial for beginners |
 | [docs/tron-encoding.md](docs/tron-encoding.md) | TRON format reference |
 | [docs/vbrief-workflow-profile.md](docs/vbrief-workflow-profile.md) | Workflow Profile extension (flow-based programming) |
-| [docs/MIGRATION.md](docs/MIGRATION.md) | v0.4 → v0.5 migration guide |
+| [docs/MIGRATION.md](docs/MIGRATION.md) | Migration guide |
 | [libvbrief-ts/README.md](libvbrief-ts/README.md) | TypeScript package usage and examples |
 
 ## Repo Structure
@@ -84,7 +84,7 @@ npm install ./libvbrief-ts
 From a fresh clone:
 
 ```bash
-git clone https://github.com/visionik/vBRIEF.git
+git clone https://github.com/deftai/vBRIEF.git
 cd vBRIEF
 pip install -e .
 npm install ./libvbrief-ts
@@ -98,7 +98,7 @@ TypeScript parsing and validation:
 import { loads, validate } from "libvbrief-ts";
 
 const document = loads(`{
-  "vBRIEFInfo": { "version": "0.5" },
+  "vBRIEFInfo": { "version": "0.7" },
   "plan": {
     "title": "Release Checklist",
     "status": "running",
@@ -137,7 +137,7 @@ python validation/vbrief_validator.py your-plan.vbrief.json
 
 ## Contributing
 
-See [CONTRIBUTING.md](CONTRIBUTING.md). Feedback and issues welcome at [GitHub Issues](https://github.com/visionik/vBRIEF/issues).
+See [CONTRIBUTING.md](CONTRIBUTING.md). Feedback and issues welcome at [GitHub Issues](https://github.com/deftai/vBRIEF/issues).
 
 ## License
 
diff --git a/docs/vbrief-spec-0.7.md b/docs/vbrief-spec-0.7.md
new file mode 100644
index 0000000..5823d89
--- /dev/null
+++ b/docs/vbrief-spec-0.7.md
@@ -0,0 +1,663 @@
+# vBRIEF Specification v0.7
+
+**Status**: Beta  
+**Date**: 2026-05-01  
+**Author**: Jonathan Taylor  
+
+## Abstract
+
+vBRIEF (Basic Relational Intent Exchange Format) is a structured document format for representing plans, tasks, workflows, and retrospectives. This specification defines the vBRIEF v0.7 data model, serialization rules, and conformance requirements. A vBRIEF document contains exactly one Plan object with optional narrative context, directed acyclic graph (DAG) edges for modeling dependencies, and nested PlanItem hierarchies using `items` as the preferred nesting field while retaining `subItems` as a deprecated compatibility alias.
+
+### Changes from v0.6
+
+- **PlanItem `type` field** — Distinguishes structural containers (`group`, `milestone`, `epic`) from actionable tasks, with automatic status rollup via `status: "auto"` (§4.5).
+- **PlanItem `summary` field** — Single-sentence shorthand description without requiring a full `narrative` object (§4.2).
+- **PlanItem `planRefs` field** — Array of plan reference URIs for container items aggregating multiple external vBRIEFs (§4.4).
+- **Extension properties** — Formal `x-<consumer>/` namespace with round-trip preservation guarantee and forward collision protection (§7).
+- **`Source` and `Confidence` narrative keys** — Recommended keys for provenance tracking on narrative facts (§3.3.1).
+- **Reference type registry** — Canonical `x-vbrief/*` types for common reference kinds (Appendix B).
+- **`failed` status** — Added to the Status enum (§5.1). Already present in v0.6 schema; now normative in spec prose.
+
+## Status of This Document
+
+This document specifies a beta release of the vBRIEF format. It is intended for early implementers and feedback. Comments and issues should be filed at <https://github.com/deftai/vBRIEF/issues>.
+
+## Table of Contents
+
+1. [Introduction](#1-introduction)
+2. [Document Structure](#2-document-structure)
+3. [Plan Object](#3-plan-object)
+4. [PlanItem Object](#4-planitem-object)
+5. [Status Enum](#5-status-enum)
+6. [DAG (Directed Acyclic Graph) Support](#6-dag-directed-acyclic-graph-support)
+7. [Extension Properties](#7-extension-properties)
+8. [TRON Encoding](#8-tron-encoding)
+9. [Conformance](#9-conformance)
+10. [Security Considerations](#10-security-considerations)
+11. [References](#11-references)
+12. [Appendix A: JSON Schema Reference](#appendix-a-json-schema-reference)
+13. [Appendix B: Reference Type Registry](#appendix-b-reference-type-registry)
+14. [Appendix C: Complete Examples](#appendix-c-complete-examples)
+
+---
+
+## 1. Introduction
+
+### 1.1 Purpose
+
+vBRIEF provides a single, portable format for capturing planning artifacts ranging from simple task lists to complex dependency graphs with retrospective narratives. It is designed for use by both humans and autonomous agents (LLMs), with particular attention to token efficiency in AI context windows.
+
+### 1.2 Terminology
+
+The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119][rfc2119].
+
+### 1.3 Design Goals
+
+1. **Graduated complexity** — A minimal document requires only four fields. Advanced features are strictly additive.
+2. **Token efficiency** — The TRON encoding provides 35–40% token reduction over JSON for LLM context windows.
+3. **Dependency modeling** — First-class DAG support for blocking relationships, conditional branches, and workflows.
+4. **Interoperability** — JSON-native with a formal JSON Schema for validation.
+5. **Extensibility** — Unknown fields MUST be preserved; custom edge types and narrative keys are permitted.
+
+---
+
+## 2. Document Structure
+
+### 2.1 Root Object
+
+A vBRIEF document is a JSON object with the following top-level fields:
+
+| Field | Type | Requirement | Description |
+|-------|------|-------------|-------------|
+| `vBRIEFInfo` | object | REQUIRED | Document metadata including format version. |
+| `plan` | object | REQUIRED | Exactly one Plan object. |
+
+A conformant document MUST contain both `vBRIEFInfo` and `plan` at the root level. A conformant document MUST NOT contain more than one `plan` object. Additional root-level fields MAY be present and MUST be preserved by implementations.
+
+### 2.2 vBRIEFInfo Object
+
+| Field | Type | Requirement | Description |
+|-------|------|-------------|-------------|
+| `version` | string | REQUIRED | Format version. MUST be `"0.7"` for this specification. |
+| `created` | string (ISO 8601) | OPTIONAL | Document creation timestamp. |
+| `updated` | string (ISO 8601) | OPTIONAL | Document last-modified timestamp. |
+| `metadata` | object | OPTIONAL | Arbitrary key-value metadata. |
+
+The `version` field MUST be the string `"0.7"` for this specification. Implementations MUST reject documents with unrecognized version strings or MAY handle them with a clear warning.
+
+---
+
+## 3. Plan Object
+
+The `plan` field contains the primary planning artifact.
+
+### 3.1 Required Fields
+
+| Field | Type | Requirement | Description |
+|-------|------|-------------|-------------|
+| `title` | string | REQUIRED | Human-readable name of the plan. |
+| `status` | string | REQUIRED | Current plan status. MUST be a valid Status enum value (see [Section 5](#5-status-enum)). |
+| `items` | array | REQUIRED | Array of PlanItem objects. MAY be empty. |
+
+### 3.2 Optional Fields
+
+| Field | Type | Description |
+|-------|------|-------------|
+| `id` | string | Stable semantic identifier for the plan. |
+| `uid` | string | Globally unique identifier (e.g., UUID). |
+| `narratives` | object | Plan-level narrative context (see [Section 3.3](#33-narratives)). |
+| `edges` | array | Array of Edge objects defining dependencies (see [Section 6](#6-dag-directed-acyclic-graph-support)). |
+| `tags` | array of strings | Categorization tags. |
+| `metadata` | object | Arbitrary key-value metadata. |
+| `created` | string (ISO 8601) | Plan creation timestamp. |
+| `updated` | string (ISO 8601) | Plan last-modified timestamp. |
+| `author` | string | Plan author identifier. |
+| `reviewers` | array of strings | Reviewer identifiers. |
+| `uris` | array of strings | Related URIs. |
+| `references` | array | Related document references. |
+| `timezone` | string | IANA timezone identifier. |
+| `agent` | string | Agent or system that created/manages the plan. |
+| `lastModifiedBy` | string | Identifier of last modifier. |
+| `changeLog` | array | Array of change records. |
+| `sequence` | integer | Monotonically increasing revision counter. |
+| `fork` | object | Fork metadata for derived plans. |
+
+### 3.3 Narratives
+
+The `narratives` field is an OPTIONAL object with string keys and string values. Each key represents a narrative category, and each value contains the narrative text.
+
+Keys SHOULD use TitleCase convention.
+
+#### 3.3.1 Recommended Planning Narrative Keys
+
+The following keys are RECOMMENDED for planning documents:
+
+- `Proposal` — What is being proposed
+- `Overview` — High-level summary
+- `Background` — Context and history
+- `Problem` — Problem statement
+- `Constraint` — Limitations and boundaries
+- `Hypothesis` — Assumptions being tested
+- `Alternative` — Other options considered
+- `Risk` — Potential issues and mitigations
+- `Test` — Validation criteria
+- `Action` — Prescribed actions
+- `Observation` — Observed outcomes
+- `Result` — Measured results
+- `Reflection` — Lessons and insights
+- `Source` — How a fact was established. RECOMMENDED values: `verified: <method>` (confirmed by a deterministic check), `observed: <method>` (seen directly), `inferred: <reason>` (derived from other facts), `assumed` (taken as true without verification; MUST be revalidated on resume).
+- `Confidence` — Agent's certainty level. RECOMMENDED values: `high`, `medium`, `low`.
+
+Consumers SHOULD treat items with `Source: assumed` or `Confidence: low` as hazards — facts to revalidate before building further reasoning on them.
+
+#### 3.3.2 Recommended Retrospective Narrative Keys
+
+The following keys are RECOMMENDED for retrospective documents:
+
+- `Outcome` — What happened
+- `Strengths` — What went well
+- `Weaknesses` — What did not go well
+- `Lessons` — What to do differently
+
+#### 3.3.3 Custom Keys
+
+Additional narrative keys are permitted. Implementations MUST preserve all narrative keys, including unrecognized ones. Custom keys SHOULD follow TitleCase convention for consistency.
+
+---
+
+## 4. PlanItem Object
+
+A PlanItem represents a single item within a plan. Items may be actionable tasks or structural containers (groups, milestones, epics) depending on their `type`.
+
+### 4.1 Required Fields
+
+| Field | Type | Requirement | Description |
+|-------|------|-------------|-------------|
+| `title` | string | REQUIRED | Human-readable item title. |
+| `status` | string | REQUIRED | Current item status. MUST be a valid Status enum value (see [Section 5](#5-status-enum)). |
+
+### 4.2 Optional Fields
+
+| Field | Type | Description |
+|-------|------|-------------|
+| `id` | string | Stable semantic identifier (see [Section 4.3](#43-hierarchical-ids)). |
+| `uid` | string | Globally unique identifier. |
+| `type` | string | Item type. MUST be one of `"task"`, `"group"`, `"milestone"`, `"epic"`. Default: `"task"`. See [Section 4.5](#45-item-types-and-status-rollup). |
+| `summary` | string | Single-sentence shorthand description. See [Section 4.6](#46-summary-field). |
+| `narrative` | object | Item-level narrative (same structure as plan narratives). |
+| `items` | array | Nested array of PlanItem objects. Preferred in v0.7 for hierarchical plans. |
+| `subItems` | array | Deprecated legacy alias for `items`. Readers SHOULD accept it for compatibility. |
+| `planRef` | string | URI referencing an external plan (see [Section 4.4](#44-plan-references-planref)). |
+| `planRefs` | array of strings | Array of plan reference URIs. See [Section 4.4](#44-plan-references-planref-and-planrefs). |
+| `tags` | array of strings | Categorization tags. |
+| `metadata` | object | Arbitrary key-value metadata. |
+| `created` | string (ISO 8601) | Item creation timestamp. |
+| `updated` | string (ISO 8601) | Item last-modified timestamp. |
+| `completed` | string (ISO 8601) | Completion timestamp. |
+| `priority` | string | Priority level (e.g., `"high"`, `"medium"`, `"low"`). |
+| `dueDate` | string (ISO 8601) | Due date. |
+| `startDate` | string (ISO 8601) | Planned start date. |
+| `endDate` | string (ISO 8601) | Planned end date. |
+| `percentComplete` | number | Completion percentage (0–100). |
+| `participants` | array of strings | Participant identifiers. |
+| `location` | string | Location context. |
+| `uris` | array of strings | Related URIs. |
+| `recurrence` | object | Recurrence rules. |
+| `reminders` | array | Reminder configurations. |
+| `classification` | string | Security or sensitivity classification. |
+| `relatedComments` | array | Associated comments or discussion. |
+| `timezone` | string | IANA timezone identifier. |
+| `sequence` | integer | Revision counter. |
+| `lastModifiedBy` | string | Identifier of last modifier. |
+| `lockedBy` | string | Lock holder identifier. |
+
+### 4.2.1 Nested Items Compatibility
+
+vBRIEF v0.6 standardizes nested PlanItem collections on the `items` field. Implementations SHOULD emit `items` when writing v0.6 documents.
+
+The legacy `subItems` field remains valid for compatibility with v0.5 tooling. Readers SHOULD accept either `items` or `subItems`. If both are present on the same PlanItem, implementations SHOULD treat `items` as canonical and MAY warn or reject the document if the two arrays diverge.
+
+### 4.3 Hierarchical IDs
+
+When the `id` field is present on a PlanItem:
+
+1. IDs MUST be user-assigned, stable, semantic strings. Implementations MUST NOT auto-generate IDs unless explicitly requested.
+2. Parent-child relationships MUST use dot notation. For example, an item `"auth"` nested under `"setup"` MUST have the ID `"setup.auth"`.
+3. IDs MUST be unique within the scope of a single Plan. Duplicate IDs within one Plan constitute a validation error.
+
+**Example:**
+
+```json
+{
+  "id": "setup",
+  "title": "Project Setup",
+  "items": [
+    { "id": "setup.auth", "title": "Authentication" },
+    { "id": "setup.auth.oauth", "title": "OAuth Integration" }
+  ]
+}
+```
+
+### 4.4 Plan References (planRef and planRefs)
+
+The `planRef` field contains a URI string referencing another plan or a specific item within a plan. The following URI schemes MUST be supported:
+
+| Syntax | Meaning | Example |
+|--------|---------|---------|
+| `#<item-id>` | Internal reference within the same plan | `"#setup.auth"` |
+| `file://<path>` | Local file reference | `"file://./backend-plan.vbrief.json"` |
+| `https://<url>` | Remote URL reference | `"https://example.com/plan.vbrief.json"` |
+
+Fragment syntax (`#`) MAY be appended to `file://` and `https://` URIs to reference a specific item within the target plan. For example: `"file://./plan.vbrief.json#setup.auth"`.
+
+Implementations MUST parse `planRef` URIs correctly. Implementations MAY defer resolution of referenced plans (lazy loading).
+
+The `planRefs` field is an OPTIONAL array of URI strings, using the same schemes as `planRef`. It allows container items (`group`, `milestone`, `epic`) to reference multiple external vBRIEFs without requiring one subItem per reference:
+
+```json
+{
+  "id": "phase2", "type": "group", "title": "Phase 2 — Stabilization",
+  "summary": "Post-cutover structural fixes and cross-cutting unblockers.",
+  "status": "auto",
+  "planRefs": [
+    "file://./pending/task-a.vbrief.json",
+    "file://./pending/task-b.vbrief.json"
+  ]
+}
+```
+
+`planRef` (singular) remains for single-reference items — no deprecation. When both are present, `planRefs` is the superset; `planRef` MAY be treated as shorthand for a single-element `planRefs`. Status rollup for `status: "auto"` items SHOULD traverse `planRefs` as well as `items`/`subItems`.
+
+### 4.5 Item Types and Status Rollup
+
+The OPTIONAL `type` field distinguishes structural containers from actionable tasks:
+
+| Value | Description |
+|-------|-------------|
+| `task` | Default. An actionable work item. |
+| `group` | Structural container with no direct action; used for phases, categories, or organizational groupings. |
+| `milestone` | A checkpoint or gate; completed when all blocking children are done. |
+| `epic` | A large container that groups tasks across multiple plans (see also: `planRefs`). |
+
+Absence of `type` implies `"task"`. Existing documents without `type` are fully conformant.
+
+When `type` is `group`, `milestone`, or `epic`, the item MAY use `status: "auto"` to signal that its status is derived from its children (`items`, `subItems`, or resolved `planRefs`):
+
+- `completed` — all children are `completed`
+- `running` — any child is `running`
+- `blocked` — any child is `blocked` and no child is `running`
+- `pending` — all children are `pending`
+- `failed` — any child is `failed` and no child is `running`
+
+`status: "auto"` MUST NOT be used on items with `type: "task"` or items with no children. Implementations MUST treat `"auto"` on a childless item as a validation error.
+
+### 4.6 Summary Field
+
+The OPTIONAL `summary` field is a plain string providing a single-sentence description of the item. It is equivalent to `narrative.Overview` for rendering purposes when `narrative` is absent.
+
+When both `summary` and `narrative` are present, `narrative` takes precedence for detailed rendering. `summary` is RECOMMENDED for container items (`group`, `milestone`, `epic`) and any task needing only a brief description.
+
+`summary` is approximately 3–4× more token-efficient than an equivalent `narrative.Overview` entry.
+
+---
+
+## 5. Status Enum
+
+### 5.1 Values
+
+Plans and PlanItems share a single universal Status enum. All status values MUST be one of:
+
+| Value | Description |
+|-------|-------------|
+| `draft` | Initial creation; not yet actionable. |
+| `proposed` | Submitted for review or approval. |
+| `approved` | Reviewed and approved; ready to begin. |
+| `pending` | Queued for execution. |
+| `running` | Actively in progress. |
+| `completed` | Successfully finished. |
+| `blocked` | Cannot proceed due to an impediment but may resume later. |
+| `failed` | Ended unsuccessfully due to an unrecoverable error or exhausted retries. |
+| `cancelled` | Abandoned intentionally; will not be completed. |
+
+Implementations MUST reject documents containing status values not in this enum, or MUST emit a validation warning.
+
+### 5.2 Lifecycle
+
+The following state transitions represent the RECOMMENDED lifecycle:
+
+```
+draft → proposed → approved → pending → running → completed
+                                           → blocked → running
+                                           → failed
+                                           → cancelled
+draft → running (quick start)
+pending → running → failed
+```
+
+Implementations are NOT REQUIRED to enforce transition order. Any status value MAY be assigned directly. The lifecycle diagram is provided as guidance for typical usage patterns.
+
+---
+
+## 6. DAG (Directed Acyclic Graph) Support
+
+The optional `edges` array on the Plan object defines dependency relationships between items, forming a directed acyclic graph.
+
+### 6.1 Edge Object
+
+| Field | Type | Requirement | Description |
+|-------|------|-------------|-------------|
+| `from` | string | REQUIRED | Source item ID. MUST reference an existing item ID within the plan. |
+| `to` | string | REQUIRED | Target item ID. MUST reference an existing item ID within the plan. |
+| `type` | string | REQUIRED | Edge type. MUST be one of the core types or a custom string. |
+
+### 6.2 Core Edge Types
+
+Implementations MUST support the following core edge types:
+
+| Type | Semantics |
+|------|-----------|
+| `blocks` | The target item MUST NOT start until the source item is completed. This is a hard dependency. |
+| `informs` | The target item benefits from the source item's context or output. This is NOT a blocking relationship. |
+| `invalidates` | Completion of the source item makes the target item unnecessary. Implementations SHOULD mark invalidated items for review. |
+| `suggests` | The source item weakly recommends the target item. There is no hard or soft dependency. |
+
+### 6.3 Edge Type Extensibility
+
+Custom edge type strings are permitted beyond the four core types. Implementations MUST support all core types as defined in [Section 6.2](#62-core-edge-types). Implementations SHOULD ignore unknown edge types gracefully (i.e., preserve them without enforcing semantics).
+
+### 6.4 Graph Constraints
+
+1. The set of edges MUST form a valid DAG. Cycles are prohibited. An edge set containing a cycle constitutes a validation error.
+2. The `from` and `to` fields of every edge MUST resolve to existing item IDs within the plan. Dangling references constitute a validation error.
+3. Implementations MUST validate DAG constraints when edges are present and MUST report violations as errors.
+
+---
+
+## 7. Extension Properties
+
+### 7.1 Namespace
+
+Property names matching the regular expression `^x-[a-z0-9-]+/` are reserved for **extension properties**. Implementations MAY include extension properties at any object level. The segment between `x-` and the first `/` is the **consumer token**, identifying the writing tool, vendor, or organization (examples: `directive`, `stream`, `acme-corp`).
+
+Consumer tokens MUST be lowercase ASCII letters, digits, and hyphens. Consumer tokens SHOULD be registered in the consumer registry at `vbrief.org/registry` to prevent collision; unregistered tokens are valid but discouraged.
+
+### 7.2 Round-Trip Preservation
+
+Implementations MUST preserve unknown extension properties verbatim on round-trip read/write. "Verbatim" means the JSON value MUST survive a round-trip through `JSON.parse(JSON.stringify(value))` — structural and value equality, not byte-for-byte identity.
+
+### 7.3 Forward Commitment
+
+Future versions of this specification MUST NOT introduce core property names matching `^x-[a-z0-9-]+/`. This guarantee is permanent and applies to all future major and minor versions.
+
+### 7.4 Scope
+
+Extension properties MAY appear at the document root, inside `vBRIEFInfo`, inside `plan`, inside `plan.metadata`, inside any value of `narratives`, inside any `PlanItem`, and inside any other object permitted by this specification.
+
+Implementations MUST validate extension property *names* against the reserved pattern but MUST NOT validate extension property *values* against any core schema constraint.
+
+### 7.5 Reserved Consumer Tokens
+
+The following consumer tokens are reserved by this specification and MUST NOT be used by external consumers: `vbrief`, `core`, `spec`, `internal`.
+
+The `x-vbrief/` prefix used by `references[].type` is a closed enum administered by this specification (see [Appendix B](#appendix-b-reference-type-registry)) and is not an open extension namespace.
+
+### 7.6 Relation to OpenAPI
+
+This extension mechanism follows the precedent established by the OpenAPI Specification's `x-` prefix (~2015). Consumer tokens SHOULD correspond to a project or organization name that the author controls. Tokens that are generic words (e.g. `x-utils/`, `x-common/`) are discouraged.
+
+---
+
+## 8. TRON Encoding
+### 8.1 Overview
+
+TRON (Token-Reduced Object Notation) is an alternative serialization of vBRIEF documents optimized for LLM context windows. TRON achieves approximately 35–40% token reduction compared to equivalent JSON by using positional class constructors and omitting redundant syntax.
+
+See [tron-encoding.md](tron-encoding.md) for the complete TRON format specification.
+
+### 8.2 Class Definitions
+
+TRON documents begin with class definitions that map positional arguments to field names:
+
+```tron
+class Edge: from, to, type
+class PlanItem: id, title, status
+```
+
+Objects are then instantiated positionally:
+
+```tron
+Edge("lint", "build", "blocks")
+PlanItem("setup", "Project Setup", "running")
+```
+
+The Plan object itself is represented as a standard key-value block, with `items` and `edges` arrays using the defined classes.
+
+### 8.3 Conformance
+
+1. A TRON document MUST be semantically equivalent to its JSON representation. No information MAY be added or lost during encoding.
+2. Round-trip conversion (TRON → JSON → TRON) MUST preserve all data.
+3. Implementations that support TRON MUST also support JSON. JSON is the canonical serialization; TRON is an optimization.
+
+---
+
+## 9. Conformance
+
+### 9.1 Conformance Criteria
+
+A document is vBRIEF v0.7 conformant if and only if:
+
+1. The root object contains a `vBRIEFInfo` field with `version` equal to `"0.7"`.
+2. The root object contains exactly one `plan` field.
+3. The `plan` object contains the REQUIRED fields: `title` (string), `status` (valid Status enum value), and `items` (array).
+4. All `status` values on the Plan and every PlanItem are valid Status enum values as defined in [Section 5.1](#51-values). `"auto"` is valid only on container items (`group`, `milestone`, `epic`) with children.
+5. If `items` or `subItems` are present on a PlanItem, every nested entry is a valid PlanItem.
+6. If `edges` are present, they form a valid DAG with no cycles.
+7. If hierarchical IDs are used, they follow dot notation as defined in [Section 4.3](#43-hierarchical-ids).
+8. Core edge types (`blocks`, `informs`, `invalidates`, `suggests`) are semantically supported.
+9. Unknown fields at any level are preserved. Extension properties matching `^x-[a-z0-9-]+/` MUST be preserved verbatim on round-trip.
+10. `planRef` and `planRefs` URIs follow the syntax defined in [Section 4.4](#44-plan-references-planref-and-planrefs).
+11. Narrative keys SHOULD use TitleCase convention.
+12. If `type` is present on a PlanItem, it MUST be one of `"task"`, `"group"`, `"milestone"`, `"epic"`.
+
+### 9.2 Implementation Requirements
+
+1. Implementations MUST preserve unknown fields when reading and writing vBRIEF documents.
+2. Implementations MUST preserve extension properties (matching `^x-[a-z0-9-]+/`) verbatim on round-trip read/write.
+3. Implementations MUST validate that all REQUIRED fields are present.
+4. Implementations SHOULD accept either `items` or `subItems` when reading nested PlanItem hierarchies.
+5. Implementations SHOULD emit `items` when writing v0.7 documents and MAY emit `subItems` only for backward compatibility.
+6. Implementations SHOULD validate DAG constraints when edges are present.
+7. Implementations MAY provide auto-correction for common issues (e.g., normalizing status casing) but MUST NOT silently drop data.
+
+---
+
+## 10. Security Considerations
+
+1. **No executable code.** vBRIEF documents MUST NOT contain executable code. Implementations MUST NOT evaluate any field value as code.
+2. **URI validation.** Implementations SHOULD validate `planRef` and `uris` values before dereferencing. Remote URIs (`https://`) introduce network dependencies and potential security risks; implementations SHOULD warn users before fetching remote references.
+3. **Document size.** Implementations SHOULD enforce reasonable limits on document size to prevent denial-of-service through excessively large documents. A RECOMMENDED maximum is 10 MB for a single document.
+4. **Sensitive data.** The `classification` field on PlanItem MAY be used to indicate sensitivity. Implementations SHOULD respect classification values when displaying or transmitting documents.
+
+---
+
+## 11. References
+
+- **[RFC 2119]** Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
+- **[vBRIEF TRON Encoding Guide]** — [tron-encoding.md](tron-encoding.md)
+- **[vBRIEF User Guide]** — [GUIDE.md](GUIDE.md)
+- **[vBRIEF JSON Schema]** — [../schemas/vbrief-core-0.7.schema.json](../schemas/vbrief-core-0.7.schema.json)
+
+[rfc2119]: https://www.rfc-editor.org/rfc/rfc2119
+
+---
+
+## Appendix A: JSON Schema Reference
+
+The normative JSON Schema for vBRIEF v0.7 is located at [`schemas/vbrief-core-0.7.schema.json`](../schemas/vbrief-core-0.7.schema.json).
+
+Implementations SHOULD use this schema for validation. The schema defines all REQUIRED fields, enum constraints, and structural rules specified in this document.
+
+---
+
+## Appendix B: Reference Type Registry
+
+The `x-vbrief/` namespace for `VBriefReference.type` is a closed enum administered by this specification. The following canonical types are defined:
+
+| Type | Description | Required fields |
+|------|-------------|----------------|
+| `x-vbrief/plan` | Reference to another vBRIEF plan document | `uri` |
+| `x-vbrief/github-issue` | GitHub issue | `uri`, `title` |
+| `x-vbrief/github-pr` | GitHub pull request | `uri`, `title` |
+| `x-vbrief/commit` | Git commit | `uri` (git SHA or URL) |
+| `x-vbrief/external` | Arbitrary external resource | `uri` |
+| `x-vbrief/research` | Research artifact or document | `uri`, `title` |
+| `x-vbrief/adr` | Architecture Decision Record | `uri`, `title` |
+
+Custom reference types SHOULD use the `x-<consumer>/` namespace (e.g. `x-myapp/ticket`) to avoid collision with the canonical registry. The `x-vbrief/` namespace is reserved for spec-defined types only.
+
+**Note:** `x-vbrief/` is the current unregistered namespace. A future `vnd.vbrief.` IANA registration path exists if the specification is submitted to IANA for formal standardization.
+
+**Example:**
+
+```json
+"references": [
+  {
+    "type": "x-vbrief/github-issue",
+    "uri": "https://github.com/owner/repo/issues/42",
+    "title": "Issue #42: Add auth module"
+  }
+]
+```
+
+---
+
+## Appendix C: Complete Examples
+
+The following examples demonstrate graduated complexity. Each is available in both JSON and TRON format in the [`examples/`](../examples/) directory.
+
+### C.1 Minimal Plan
+
+**JSON** ([`examples/minimal-plan.vbrief.json`](../examples/minimal-plan.vbrief.json)):
+
+```json
+{
+  "vBRIEFInfo": { "version": "0.7" },
+  "plan": {
+    "title": "Daily Tasks",
+    "status": "running",
+    "items": [
+      { "title": "Fix authentication bug", "status": "pending" },
+      { "title": "Review PR #123", "status": "running" }
+    ]
+  }
+}
+```
+
+### C.2 Structured Plan with Container Types (v0.7)
+
+```json
+{
+  "vBRIEFInfo": { "version": "0.7" },
+  "plan": {
+    "id": "project-rollout",
+    "title": "Project Rollout",
+    "status": "running",
+    "items": [
+      {
+        "id": "phase1",
+        "type": "group",
+        "title": "Phase 1 — Foundation",
+        "summary": "Core infrastructure and authentication.",
+        "status": "auto",
+        "items": [
+          { "id": "phase1.auth", "title": "Authentication module", "status": "completed" },
+          { "id": "phase1.db", "title": "Database schema", "status": "running" }
+        ]
+      },
+      {
+        "id": "phase2",
+        "type": "group",
+        "title": "Phase 2 — Stabilization",
+        "summary": "Post-cutover structural fixes and cross-cutting unblockers.",
+        "status": "auto",
+        "planRefs": [
+          "file://./pending/task-a.vbrief.json",
+          "file://./pending/task-b.vbrief.json"
+        ]
+      },
+      {
+        "id": "ga",
+        "type": "milestone",
+        "title": "GA Release",
+        "summary": "All phase 1 and 2 items complete; production-ready.",
+        "status": "pending"
+      }
+    ],
+    "edges": [
+      { "from": "phase1", "to": "phase2", "type": "blocks" },
+      { "from": "phase2", "to": "ga", "type": "blocks" }
+    ]
+  }
+}
+```
+
+### C.3 Provenance Tracking with Source and Confidence
+
+```json
+{
+  "vBRIEFInfo": { "version": "0.7" },
+  "plan": {
+    "title": "Auth Module Investigation",
+    "status": "completed",
+    "items": [
+      {
+        "id": "verify-tests",
+        "title": "Verify edge-case tests pass",
+        "status": "completed",
+        "narrative": {
+          "Outcome": "Auth module passes all edge case tests",
+          "Source": "verified: task check",
+          "Confidence": "high"
+        }
+      },
+      {
+        "id": "check-db",
+        "title": "Check test DB fixtures",
+        "status": "completed",
+        "narrative": {
+          "Outcome": "Test DB appears to be seeded with fixture data",
+          "Source": "assumed",
+          "Confidence": "low"
+        }
+      }
+    ]
+  }
+}
+```
+
+### C.4 DAG Plan
+
+**JSON** ([`examples/dag-plan.vbrief.json`](../examples/dag-plan.vbrief.json)):
+
+```json
+{
+  "vBRIEFInfo": { "version": "0.7" },
+  "plan": {
+    "id": "ci-pipeline",
+    "title": "CI Pipeline",
+    "status": "running",
+    "items": [
+      { "id": "lint", "title": "Lint", "status": "completed" },
+      { "id": "test", "title": "Test", "status": "running" },
+      { "id": "build", "title": "Build", "status": "pending" },
+      { "id": "deploy", "title": "Deploy", "status": "pending" }
+    ],
+    "edges": [
+      { "from": "lint", "to": "build", "type": "blocks" },
+      { "from": "test", "to": "build", "type": "blocks" },
+      { "from": "build", "to": "deploy", "type": "blocks" },
+      { "from": "lint", "to": "test", "type": "informs" }
+    ]
+  }
+}
+```
diff --git a/examples/construction-project-gantt.vbrief.json b/examples/construction-project-gantt.vbrief.json
index e6b9452..9ea20bc 100644
--- a/examples/construction-project-gantt.vbrief.json
+++ b/examples/construction-project-gantt.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5",
+    "version": "0.7",
     "created": "2026-02-07T04:48:00Z"
   },
   "plan": {
diff --git a/examples/dag-plan.vbrief.json b/examples/dag-plan.vbrief.json
index 406a283..3cc9a65 100644
--- a/examples/dag-plan.vbrief.json
+++ b/examples/dag-plan.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5",
+    "version": "0.7",
     "created": "2026-02-03T09:00:00Z"
   },
   "plan": {
diff --git a/examples/invalid-cycle.vbrief.json b/examples/invalid-cycle.vbrief.json
index 9e18e2d..3ce6c6a 100644
--- a/examples/invalid-cycle.vbrief.json
+++ b/examples/invalid-cycle.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5"
+    "version": "0.7"
   },
   "plan": {
     "title": "Invalid Plan with Cycle",
diff --git a/examples/minimal-plan.vbrief.json b/examples/minimal-plan.vbrief.json
index b78a809..1785bfb 100644
--- a/examples/minimal-plan.vbrief.json
+++ b/examples/minimal-plan.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5"
+    "version": "0.7"
   },
   "plan": {
     "title": "Daily Tasks",
diff --git a/examples/prd.vbrief.json b/examples/prd.vbrief.json
index b1dd38a..e9f42e4 100644
--- a/examples/prd.vbrief.json
+++ b/examples/prd.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5"
+    "version": "0.7"
   },
   "plan": {
     "title": "SQLite UI PRD",
diff --git a/examples/retrospective-plan.vbrief.json b/examples/retrospective-plan.vbrief.json
index 1a6aa29..9dd754e 100644
--- a/examples/retrospective-plan.vbrief.json
+++ b/examples/retrospective-plan.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5",
+    "version": "0.7",
     "created": "2026-02-03T09:00:00Z"
   },
   "plan": {
diff --git a/examples/rfc854.vbrief.json b/examples/rfc854.vbrief.json
index 09aa517..dbe2cd7 100644
--- a/examples/rfc854.vbrief.json
+++ b/examples/rfc854.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5"
+    "version": "0.7"
   },
   "plan": {
     "title": "RFC 854: TELNET Protocol Specification",
diff --git a/examples/software-development-gantt.vbrief.json b/examples/software-development-gantt.vbrief.json
index 94cbf51..57563b8 100644
--- a/examples/software-development-gantt.vbrief.json
+++ b/examples/software-development-gantt.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5",
+    "version": "0.7",
     "created": "2026-02-07T04:48:00Z"
   },
   "plan": {
diff --git a/examples/structured-plan.vbrief.json b/examples/structured-plan.vbrief.json
index a23dd00..e7fdbf0 100644
--- a/examples/structured-plan.vbrief.json
+++ b/examples/structured-plan.vbrief.json
@@ -1,6 +1,6 @@
 {
   "vBRIEFInfo": {
-    "version": "0.5",
+    "version": "0.7",
     "created": "2026-02-03T09:00:00Z"
   },
   "plan": {
diff --git a/examples/workflow-invoice-processing.vbrief.json b/examples/workflow-invoice-processing.vbrief.json
index 24f0e37..feb35be 100644
--- a/examples/workflow-invoice-processing.vbrief.json
+++ b/examples/workflow-invoice-processing.vbrief.json
@@ -1,5 +1,5 @@
 {
-  "vBRIEFInfo": { "version": "0.5" },
+  "vBRIEFInfo": { "version": "0.7" },
   "plan": {
     "id": "wf:invoice-processing-v4",
     "title": "Invoice Processing with Error Handling",
diff --git a/libvbrief/compat/__init__.py b/libvbrief/compat/__init__.py
index 1f401fe..ec0661c 100644
--- a/libvbrief/compat/__init__.py
+++ b/libvbrief/compat/__init__.py
@@ -1,6 +1,7 @@
 """Compatibility helpers and policy constants."""
 
 from libvbrief.compat.policy import (
+    EXTENSION_PROPERTY_PATTERN,
     HIERARCHICAL_ID_PATTERN,
     ISSUE_DAG_CYCLE,
     ISSUE_DANGLING_EDGE_REF,
@@ -10,7 +11,9 @@
     ISSUE_INVALID_ID_FORMAT,
     ISSUE_INVALID_ITEM_STATUS,
     ISSUE_INVALID_ITEM_TYPE,
+    ISSUE_INVALID_ITEM_TYPE_VALUE,
     ISSUE_INVALID_PLANREF,
+    ISSUE_INVALID_PLANREFS,
     ISSUE_INVALID_PLAN_FIELD_TYPE,
     ISSUE_INVALID_PLAN_STATUS,
     ISSUE_INVALID_ROOT_FIELD_TYPE,
@@ -20,7 +23,9 @@
     ISSUE_MISSING_PLAN_FIELD,
     ISSUE_MISSING_ROOT_FIELD,
     PLAN_REF_PATTERN,
+    VALID_ITEM_TYPES,
     VALID_STATUSES,
+    VALID_VERSIONS,
 )
 
 __all__ = [
diff --git a/libvbrief/compat/policy.py b/libvbrief/compat/policy.py
index 073cf7c..f95f76c 100644
--- a/libvbrief/compat/policy.py
+++ b/libvbrief/compat/policy.py
@@ -13,9 +13,28 @@
     "running",
     "completed",
     "blocked",
+    "failed",
     "cancelled",
+    "auto",
 }
 
+VALID_ITEM_TYPES: Final[set[str]] = {
+    "task",
+    "group",
+    "milestone",
+    "epic",
+}
+
+VALID_VERSIONS: Final[set[str]] = {
+    "0.5",
+    "0.6",
+    "0.7",
+}
+
+EXTENSION_PROPERTY_PATTERN: Final[re.Pattern[str]] = re.compile(
+    r"^x-[a-z0-9-]+/"
+)
+
 HIERARCHICAL_ID_PATTERN: Final[re.Pattern[str]] = re.compile(
     r"^[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)*$"
 )
@@ -43,3 +62,5 @@
 ISSUE_INVALID_EDGE_STRUCTURE: Final[str] = "invalid_edge_structure"
 ISSUE_DANGLING_EDGE_REF: Final[str] = "dangling_edge_ref"
 ISSUE_DAG_CYCLE: Final[str] = "dag_cycle"
+ISSUE_INVALID_ITEM_TYPE_VALUE: Final[str] = "invalid_item_type_value"
+ISSUE_INVALID_PLANREFS: Final[str] = "invalid_planrefs"
diff --git a/libvbrief/models.py b/libvbrief/models.py
index 15f0ffc..756d057 100644
--- a/libvbrief/models.py
+++ b/libvbrief/models.py
@@ -1,4 +1,4 @@
-"""Dataclass object model for vBRIEF v0.5 documents."""
+"""Dataclass object model for vBRIEF v0.7 documents."""
 
 from __future__ import annotations
 
@@ -13,11 +13,15 @@
 _PLAN_ITEM_FIELD_ORDER = [
     "id",
     "uid",
+    "type",
+    "summary",
     "title",
     "status",
     "narrative",
+    "items",
     "subItems",
     "planRef",
+    "planRefs",
     "tags",
     "metadata",
     "created",
@@ -76,9 +80,13 @@ class PlanItem:
     status: str = ""
     id: Any = None
     uid: Any = None
+    type: Any = None
+    summary: Any = None
     narrative: Any = None
+    items: list[PlanItem] = field(default_factory=list)
     subItems: list[PlanItem] = field(default_factory=list)
     planRef: Any = None
+    planRefs: Any = None
     tags: Any = None
     metadata: Any = None
     created: Any = None
@@ -141,10 +149,13 @@ def from_dict(cls, data: Mapping[str, Any]) -> PlanItem:
         item = cls(
             id=data.get("id"),
             uid=data.get("uid"),
+            type=data.get("type"),
+            summary=data.get("summary"),
             title=data.get("title", ""),
             status=data.get("status", ""),
             narrative=data.get("narrative"),
             planRef=data.get("planRef"),
+            planRefs=data.get("planRefs"),
             tags=data.get("tags"),
             metadata=data.get("metadata"),
             created=data.get("created"),
@@ -170,6 +181,10 @@ def from_dict(cls, data: Mapping[str, Any]) -> PlanItem:
             _field_order=list(data.keys()),
         )
 
+        items_field = data.get("items")
+        if isinstance(items_field, list):
+            item.items = [cls.from_dict(x) for x in items_field if isinstance(x, Mapping)]
+
         sub_items = data.get("subItems")
         if isinstance(sub_items, list):
             # Non-Mapping entries are intentionally skipped (lenient parse);
@@ -376,11 +391,17 @@ def _known_item_values(item: PlanItem, *, preserve_order: bool) -> dict[str, Any
     optional_pairs = {
         "id": item.id,
         "uid": item.uid,
+        "type": item.type,
+        "summary": item.summary,
         "narrative": item.narrative,
+        "items": [sub.to_dict(preserve_order=preserve_order) for sub in item.items]
+        if item.items
+        else None,
         "subItems": [sub.to_dict(preserve_order=preserve_order) for sub in item.subItems]
         if item.subItems
         else None,
         "planRef": item.planRef,
+        "planRefs": item.planRefs,
         "tags": item.tags,
         "metadata": item.metadata,
         "created": item.created,
diff --git a/libvbrief/validation.py b/libvbrief/validation.py
index 3511bb3..e17cac9 100644
--- a/libvbrief/validation.py
+++ b/libvbrief/validation.py
@@ -1,4 +1,4 @@
-"""Core conformance validation for vBRIEF v0.5 JSON documents."""
+"""Core conformance validation for vBRIEF v0.7 JSON documents."""
 
 from __future__ import annotations
 
@@ -11,7 +11,9 @@
     ISSUE_INVALID_ID_FORMAT,
     ISSUE_INVALID_ITEM_STATUS,
     ISSUE_INVALID_ITEM_TYPE,
+    ISSUE_INVALID_ITEM_TYPE_VALUE,
     ISSUE_INVALID_PLANREF,
+    ISSUE_INVALID_PLANREFS,
     ISSUE_INVALID_PLAN_FIELD_TYPE,
     ISSUE_INVALID_PLAN_STATUS,
     ISSUE_INVALID_ROOT_FIELD_TYPE,
@@ -21,7 +23,9 @@
     ISSUE_MISSING_PLAN_FIELD,
     ISSUE_MISSING_ROOT_FIELD,
     PLAN_REF_PATTERN,
+    VALID_ITEM_TYPES,
     VALID_STATUSES,
+    VALID_VERSIONS,
 )
 from libvbrief.issues import ValidationReport
 
@@ -73,11 +77,11 @@ def _validate_root(data: Mapping[str, Any], report: ValidationReport) -> None:
 
     if vbrief_info is not None:
         version = vbrief_info.get("version")
-        if version != "0.5":
+        if version not in VALID_VERSIONS:
             report.add_error(
                 ISSUE_INVALID_VERSION,
                 "vBRIEFInfo.version",
-                f"Expected version '0.5', got {version!r}",
+                f"Expected version in {sorted(VALID_VERSIONS)}, got {version!r}",
             )
 
     if "plan" not in data:
@@ -188,6 +192,14 @@ def _validate_items(
             else:
                 seen_ids.add(item_id)
 
+        item_type = item.get("type")
+        if item_type is not None and item_type not in VALID_ITEM_TYPES:
+            report.add_error(
+                ISSUE_INVALID_ITEM_TYPE_VALUE,
+                f"{item_path}.type",
+                f"Invalid item type {item_type!r}; expected one of {sorted(VALID_ITEM_TYPES)}",
+            )
+
         plan_ref = item.get("planRef")
         if plan_ref is not None and (not isinstance(plan_ref, str) or not PLAN_REF_PATTERN.match(plan_ref)):
             report.add_error(
@@ -196,6 +208,23 @@ def _validate_items(
                 "planRef must match #..., file://..., or https://...",
             )
 
+        plan_refs = item.get("planRefs")
+        if plan_refs is not None:
+            if not isinstance(plan_refs, list):
+                report.add_error(
+                    ISSUE_INVALID_PLANREFS,
+                    f"{item_path}.planRefs",
+                    "planRefs must be an array",
+                )
+            else:
+                for idx, ref in enumerate(plan_refs):
+                    if not isinstance(ref, str) or not PLAN_REF_PATTERN.match(ref):
+                        report.add_error(
+                            ISSUE_INVALID_PLANREFS,
+                            f"{item_path}.planRefs[{idx}]",
+                            "planRefs entries must match #..., file://..., or https://...",
+                        )
+
         sub_items = item.get("subItems")
         if sub_items is None:
             continue
diff --git a/schemas/vbrief-core-0.7.schema.json b/schemas/vbrief-core-0.7.schema.json
new file mode 100644
index 0000000..08fe728
--- /dev/null
+++ b/schemas/vbrief-core-0.7.schema.json
@@ -0,0 +1,772 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://vbrief.dev/schemas/vbrief-core-0.7.schema.json",
+  "title": "vBRIEF Core Schema v0.7",
+  "description": "JSON Schema for vBRIEF core document structure (v0.7). Adds PlanItem type (task/group/milestone/epic), summary, planRefs, extension property namespace (x-<consumer>/), Source/Confidence narrative keys, and reference type registry.",
+  "type": "object",
+  "required": [
+    "vBRIEFInfo",
+    "plan"
+  ],
+  "properties": {
+    "vBRIEFInfo": {
+      "$ref": "#/$defs/vBRIEFInfo"
+    },
+    "plan": {
+      "$ref": "#/$defs/Plan"
+    }
+  },
+  "additionalProperties": true,
+  "patternProperties": {
+    "^x-[a-z0-9-]+/": {
+      "description": "Extension property. Consumer-scoped; MUST be preserved verbatim on round-trip."
+    }
+  },
+  "not": {
+    "anyOf": [
+      {
+        "required": [
+          "todoList"
+        ]
+      },
+      {
+        "required": [
+          "playbook"
+        ]
+      }
+    ]
+  },
+  "$defs": {
+    "vBRIEFInfo": {
+      "type": "object",
+      "required": [
+        "version"
+      ],
+      "properties": {
+        "version": {
+          "type": "string",
+          "const": "0.7"
+        },
+        "author": {
+          "type": "string"
+        },
+        "description": {
+          "type": "string"
+        },
+        "metadata": {
+          "type": "object"
+        },
+        "created": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "updated": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "timezone": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": true,
+      "patternProperties": {
+        "^x-[a-z0-9-]+/": {}
+      }
+    },
+    "Plan": {
+      "type": "object",
+      "required": [
+        "title",
+        "status",
+        "items"
+      ],
+      "properties": {
+        "id": {
+          "type": "string",
+          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
+        },
+        "uid": {
+          "type": "string"
+        },
+        "title": {
+          "type": "string",
+          "minLength": 1
+        },
+        "status": {
+          "$ref": "#/$defs/Status"
+        },
+        "items": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/PlanItem"
+          }
+        },
+        "narratives": {
+          "type": "object",
+          "properties": {
+            "Proposal": {
+              "type": "string"
+            },
+            "Overview": {
+              "type": "string"
+            },
+            "Background": {
+              "type": "string"
+            },
+            "Problem": {
+              "type": "string"
+            },
+            "Constraint": {
+              "type": "string"
+            },
+            "Hypothesis": {
+              "type": "string"
+            },
+            "Alternative": {
+              "type": "string"
+            },
+            "Risk": {
+              "type": "string"
+            },
+            "Test": {
+              "type": "string"
+            },
+            "Action": {
+              "type": "string"
+            },
+            "Observation": {
+              "type": "string"
+            },
+            "Result": {
+              "type": "string"
+            },
+            "Reflection": {
+              "type": "string"
+            },
+            "Outcome": {
+              "type": "string"
+            },
+            "Strengths": {
+              "type": "string"
+            },
+            "Weaknesses": {
+              "type": "string"
+            },
+            "Lessons": {
+              "type": "string"
+            },
+            "Source": {
+              "type": "string",
+              "description": "How a fact was established. Recommended values: verified:<method>, observed:<method>, inferred:<reason>, assumed."
+            },
+            "Confidence": {
+              "type": "string",
+              "description": "Agent certainty level. Recommended values: high, medium, low."
+            }
+          },
+          "additionalProperties": {
+            "type": "string"
+          }
+        },
+        "edges": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/Edge"
+          }
+        },
+        "tags": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "metadata": {
+          "type": "object"
+        },
+        "created": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "updated": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "author": {
+          "type": "string"
+        },
+        "reviewers": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "uris": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/URI"
+          }
+        },
+        "references": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/VBriefReference"
+          }
+        },
+        "timezone": {
+          "type": "string"
+        },
+        "agent": {
+          "$ref": "#/$defs/Agent"
+        },
+        "lastModifiedBy": {
+          "$ref": "#/$defs/Agent"
+        },
+        "changeLog": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/Change"
+          }
+        },
+        "sequence": {
+          "type": "integer",
+          "minimum": 0
+        },
+        "fork": {
+          "$ref": "#/$defs/Fork"
+        }
+      },
+      "additionalProperties": true,
+      "patternProperties": {
+        "^x-[a-z0-9-]+/": {}
+      }
+    },
+    "PlanItem": {
+      "type": "object",
+      "required": [
+        "title",
+        "status"
+      ],
+      "properties": {
+        "id": {
+          "type": "string",
+          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
+        },
+        "uid": {
+          "type": "string"
+        },
+        "type": {
+          "type": "string",
+          "enum": ["task", "group", "milestone", "epic"],
+          "default": "task",
+          "description": "Item type. Containers (group, milestone, epic) support status rollup."
+        },
+        "summary": {
+          "type": "string",
+          "description": "Single-sentence shorthand description. Equivalent to narrative.Overview when narrative is absent."
+        },
+        "title": {
+          "type": "string",
+          "minLength": 1
+        },
+        "status": {
+          "$ref": "#/$defs/Status"
+        },
+        "narrative": {
+          "type": "object",
+          "additionalProperties": {
+            "type": "string"
+          }
+        },
+        "subItems": {
+          "type": "array",
+          "description": "Deprecated legacy alias for items; retained for compatibility.",
+          "items": {
+            "$ref": "#/$defs/PlanItem"
+          }
+        },
+        "planRef": {
+          "type": "string",
+          "pattern": "^(#[a-zA-Z0-9_.-]+|file://.*|https://.*)$"
+        },
+        "planRefs": {
+          "type": "array",
+          "description": "Array of plan reference URIs for container items aggregating multiple external vBRIEFs.",
+          "items": {
+            "type": "string",
+            "pattern": "^(#[a-zA-Z0-9_.-]+|file://.*|https://.*)$"
+          }
+        },
+        "tags": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "metadata": {
+          "type": "object"
+        },
+        "created": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "updated": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "completed": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "priority": {
+          "enum": [
+            "low",
+            "medium",
+            "high",
+            "critical"
+          ]
+        },
+        "dueDate": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "startDate": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "endDate": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "percentComplete": {
+          "type": "number",
+          "minimum": 0,
+          "maximum": 100
+        },
+        "participants": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/Participant"
+          }
+        },
+        "location": {
+          "$ref": "#/$defs/Location"
+        },
+        "uris": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/URI"
+          }
+        },
+        "recurrence": {
+          "$ref": "#/$defs/RecurrenceRule"
+        },
+        "reminders": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/Reminder"
+          }
+        },
+        "classification": {
+          "enum": [
+            "public",
+            "private",
+            "confidential"
+          ]
+        },
+        "relatedComments": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "timezone": {
+          "type": "string"
+        },
+        "sequence": {
+          "type": "integer",
+          "minimum": 0
+        },
+        "lastModifiedBy": {
+          "$ref": "#/$defs/Agent"
+        },
+        "lockedBy": {
+          "$ref": "#/$defs/Lock"
+        },
+        "items": {
+          "type": "array",
+          "description": "Preferred v0.6 nested PlanItem field.",
+          "items": {
+            "$ref": "#/$defs/PlanItem"
+          }
+        }
+      },
+      "additionalProperties": true,
+      "patternProperties": {
+        "^x-[a-z0-9-]+/": {}
+      }
+    },
+    "Status": {
+      "enum": [
+        "draft",
+        "proposed",
+        "approved",
+        "pending",
+        "running",
+        "completed",
+        "blocked",
+        "failed",
+        "cancelled",
+        "auto"
+      ],
+      "description": "Universal status enum. 'auto' is valid only on container items (group, milestone, epic) with children."
+    },
+    "Edge": {
+      "type": "object",
+      "required": [
+        "from",
+        "to",
+        "type"
+      ],
+      "properties": {
+        "from": {
+          "type": "string",
+          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
+        },
+        "to": {
+          "type": "string",
+          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
+        },
+        "type": {
+          "type": "string",
+          "description": "Core types: blocks, informs, invalidates, suggests. Custom types allowed."
+        }
+      },
+      "additionalProperties": true
+    },
+    "Participant": {
+      "type": "object",
+      "required": [
+        "id",
+        "role"
+      ],
+      "properties": {
+        "id": {
+          "type": "string"
+        },
+        "name": {
+          "type": "string"
+        },
+        "email": {
+          "type": "string"
+        },
+        "role": {
+          "enum": [
+            "owner",
+            "assignee",
+            "reviewer",
+            "observer",
+            "contributor"
+          ]
+        },
+        "status": {
+          "enum": [
+            "accepted",
+            "declined",
+            "tentative",
+            "needsAction"
+          ]
+        }
+      },
+      "additionalProperties": true
+    },
+    "URI": {
+      "type": "object",
+      "required": [
+        "uri"
+      ],
+      "properties": {
+        "uri": {
+          "type": "string"
+        },
+        "description": {
+          "type": "string"
+        },
+        "type": {
+          "type": "string"
+        },
+        "title": {
+          "type": "string"
+        },
+        "tags": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        }
+      },
+      "additionalProperties": true
+    },
+    "VBriefReference": {
+      "allOf": [
+        {
+          "$ref": "#/$defs/URI"
+        },
+        {
+          "type": "object",
+          "required": [
+            "uri",
+            "type"
+          ],
+          "properties": {
+            "type": {
+              "type": "string",
+              "pattern": "^x-vbrief/",
+              "description": "A vBRIEF reference type. Canonical types: x-vbrief/plan, x-vbrief/github-issue, x-vbrief/github-pr, x-vbrief/commit, x-vbrief/external, x-vbrief/research, x-vbrief/adr. Custom types SHOULD use x-<consumer>/ namespace."
+            }
+          }
+        }
+      ]
+    },
+    "Location": {
+      "type": "object",
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "address": {
+          "type": "string"
+        },
+        "geo": {
+          "type": "array",
+          "minItems": 2,
+          "maxItems": 2,
+          "items": {
+            "type": "number"
+          }
+        },
+        "url": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": true
+    },
+    "RecurrenceRule": {
+      "type": "object",
+      "required": [
+        "frequency"
+      ],
+      "properties": {
+        "frequency": {
+          "enum": [
+            "daily",
+            "weekly",
+            "monthly",
+            "yearly"
+          ]
+        },
+        "interval": {
+          "type": "integer",
+          "minimum": 1
+        },
+        "until": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "count": {
+          "type": "integer",
+          "minimum": 1
+        },
+        "byDay": {
+          "type": "array",
+          "items": {
+            "enum": [
+              "MO",
+              "TU",
+              "WE",
+              "TH",
+              "FR",
+              "SA",
+              "SU"
+            ]
+          }
+        },
+        "byMonth": {
+          "type": "array",
+          "items": {
+            "type": "integer",
+            "minimum": 1,
+            "maximum": 12
+          }
+        },
+        "byMonthDay": {
+          "type": "array",
+          "items": {
+            "type": "integer",
+            "minimum": 1,
+            "maximum": 31
+          }
+        }
+      },
+      "additionalProperties": true
+    },
+    "Reminder": {
+      "type": "object",
+      "required": [
+        "trigger",
+        "action"
+      ],
+      "properties": {
+        "trigger": {
+          "type": "string"
+        },
+        "action": {
+          "enum": [
+            "display",
+            "email",
+            "webhook",
+            "audio"
+          ]
+        },
+        "description": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": true
+    },
+    "Agent": {
+      "type": "object",
+      "required": [
+        "id",
+        "type"
+      ],
+      "properties": {
+        "id": {
+          "type": "string"
+        },
+        "type": {
+          "enum": [
+            "human",
+            "aiAgent",
+            "system"
+          ]
+        },
+        "name": {
+          "type": "string"
+        },
+        "email": {
+          "type": "string"
+        },
+        "model": {
+          "type": "string"
+        },
+        "version": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": true
+    },
+    "Change": {
+      "type": "object",
+      "required": [
+        "sequence",
+        "timestamp",
+        "agent",
+        "operation"
+      ],
+      "properties": {
+        "sequence": {
+          "type": "integer",
+          "minimum": 0
+        },
+        "timestamp": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "agent": {
+          "$ref": "#/$defs/Agent"
+        },
+        "operation": {
+          "enum": [
+            "create",
+            "update",
+            "delete",
+            "fork",
+            "merge"
+          ]
+        },
+        "reason": {
+          "type": "string"
+        },
+        "path": {
+          "type": "string"
+        },
+        "oldValue": {},
+        "newValue": {},
+        "description": {
+          "type": "string"
+        },
+        "snapshotUri": {
+          "type": "string"
+        },
+        "relatedChanges": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        }
+      },
+      "additionalProperties": true
+    },
+    "Fork": {
+      "type": "object",
+      "required": [
+        "parentUid",
+        "parentSequence",
+        "forkedAt"
+      ],
+      "properties": {
+        "parentUid": {
+          "type": "string"
+        },
+        "parentSequence": {
+          "type": "integer",
+          "minimum": 0
+        },
+        "forkedAt": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "forkReason": {
+          "type": "string"
+        },
+        "mergeStatus": {
+          "enum": [
+            "unmerged",
+            "mergePending",
+            "merged",
+            "conflict"
+          ]
+        }
+      },
+      "additionalProperties": true
+    },
+    "Lock": {
+      "type": "object",
+      "required": [
+        "agent",
+        "acquiredAt",
+        "type"
+      ],
+      "properties": {
+        "agent": {
+          "$ref": "#/$defs/Agent"
+        },
+        "acquiredAt": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "expiresAt": {
+          "$ref": "#/$defs/dateTime"
+        },
+        "type": {
+          "enum": [
+            "soft",
+            "hard"
+          ]
+        }
+      },
+      "additionalProperties": true
+    },
+    "dateTime": {
+      "type": "string",
+      "format": "date-time",
+      "pattern": "(Z|[+-]\\d{2}:\\d{2})$"
+    }
+  }
+}