doc updates

docs/architecture.md

@@ -16,11 +16,17 @@ The system is complete in three layers:
 2. Catalog resources provide normalized discovery.
 3. Zensical builds a static site from those same Markdown sources and the FastAPI app serves it in the FastMCP runtime process.
 
-For Phase 1, this architecture is anchored by three contracts:
+This architecture is anchored by three contracts:
 
-1. Step 1: docs-first authored content contract under `docs/` with strict per-skill ownership.
+1. Docs-first authored content contract under `docs/` with strict per-skill ownership.
-2. Step 2: SKILL.md frontmatter contract with Anthropic fields plus `x-personal-mcp` metadata.
+2. `SKILL.md` frontmatter contract with Anthropic fields plus `x-personal-mcp` metadata.
-3. Step 3: canonical resource URI contract with break-and-replace policy for contract changes.
+3. Canonical resource URI contract with break-and-replace policy for contract changes.
+
+Detailed contract pages:
+
+1. [Content Contract](./content.md)
+2. [Frontmatter Contract](./frontmatter.md)
+3. [URI Contract](./uris.md)
 
 This architecture keeps authored content human-friendly while preserving machine-stable contracts.
 
@@ -62,7 +68,7 @@ Only canonical catalog resources are part of the runtime contract in this phase.
 
 ### Registry Loader
 
-Phase 2 runtime composition introduces a startup registry loader that reads packaged docs resources using `importlib.resources.files(...)` and `Traversable` APIs.
+The runtime composition includes a startup registry loader that reads packaged docs resources using `importlib.resources.files(...)` and `Traversable` APIs.
 
 Loader responsibilities:
 
@@ -104,6 +110,8 @@ flowchart TD
 
 Each skill declares frontmatter in `docs/skills/<skill-id>/SKILL.md`.
 
+For the full field-level contract, validation model, and FastMCP metadata mapping, see [Frontmatter Contract](./frontmatter.md).
+
 Anthropic-facing required fields:
 
 1. name
@@ -124,6 +132,8 @@ No `metadata.yaml` sidecar is part of the end-state contract.
 
 Canonical resource URIs are:
 
+For the full URI semantics, parameter validation rules, and compatibility policy, see [URI Contract](./uris.md).
+
 1. resource://skills/<skill_id>/document
 2. resource://skills/<skill_id>/references/<ref_id>
 3. resource://catalog/skills_index

docs/content.md

@@ -0,0 +1,84 @@
+# Content Contract
+
+This page defines the authored content contract for the docs-first MCP architecture.
+
+## Canonical Source Of Truth
+
+1. All authored Markdown lives under `docs/`.
+2. MCP resources and static docs are two distribution surfaces of the same authored files.
+3. No parallel authored markdown is allowed in `src/` or other package-only paths.
+
+## Canonical Skill Shape
+
+Each skill is one directory under `docs/skills/`:
+
+```text
+docs/
+  skills/
+    <skill-id>/
+      SKILL.md
+      references/
+        ... (one or more markdown files, optional nested folders)
+```
+
+Rules:
+
+1. `SKILL.md` is required for every skill.
+2. `references/` is the only place for skill-specific supporting docs.
+3. Nested folders inside `references/` are allowed so a skill can reorganize internals without changing global architecture.
+4. Skill directories are independent ownership boundaries; no cross-skill file writes.
+
+## File Placement And Ownership Boundaries
+
+1. Top-level project docs stay in `docs/*.md`.
+2. Skill docs stay in `docs/skills/<skill-id>/...`.
+3. A skill may link to other skills, but must not store content inside another skill's directory.
+4. Server and runtime code may index and serve docs, but must not be the source of authored markdown.
+
+## Metadata Location Constraint
+
+1. Skill metadata is embedded in YAML frontmatter in `SKILL.md`.
+2. No `metadata.yaml` sidecar exists in the end state.
+3. Reference lookup metadata, including reference id to relative path mappings, is declared from `SKILL.md` frontmatter rather than inferred as a hidden global convention.
+
+## Skill Id Contract
+
+`skill-id` is the public identifier and should satisfy all rules below:
+
+1. Format: lowercase kebab-case only.
+2. Character set: `a-z`, `0-9`, and `-`.
+3. Must start with a letter.
+4. No underscores, spaces, dots, or uppercase characters.
+5. Directory name should equal `skill-id` in each committed revision.
+6. Frontmatter `id` should equal directory name in each committed revision.
+7. Treat `skill-id` as immutable after release; any rename is a breaking replacement and clients must move to the new id.
+
+Valid examples:
+
+1. `fastapi-uv-docker`
+2. `zensical-docs`
+3. `pytest-scaffolding`
+
+Invalid examples:
+
+1. `fastapi_uv_docker`
+2. `Zensical-Docs`
+3. `docs.zensical`
+
+## Invariants
+
+This contract guarantees:
+
+1. One authored source tree in `docs/` for both website and MCP.
+2. One skill directory maps to one skill identity per revision.
+3. Namespace and slug drift is minimized by keeping directory and frontmatter ids aligned per revision.
+4. Per-skill reference structure can evolve without changing cross-skill architecture.
+5. Packaging for stdio is deterministic because authored content is path-stable.
+
+## Non-Goals
+
+This contract does not define:
+
+1. URI versioning policy details.
+2. The full frontmatter schema.
+3. Migration instructions from the current architecture.

docs/frontmatter.md

@@ -0,0 +1,309 @@
+# Frontmatter Contract
+
+This page defines the `SKILL.md` frontmatter and FastMCP metadata contract.
+
+## Anthropic Frontmatter Support
+
+Across Anthropic API and Agent Skills surfaces:
+
+1. Required fields for custom skill bundles are `name` and `description`.
+2. `name` must be 1-64 characters, lowercase letters, numbers, and hyphens only, with no XML tags, and must not use the reserved words `anthropic` or `claude`.
+3. `description` must be 1-1024 characters, non-empty, and contain no XML tags.
+
+Portable optional fields from the Agent Skills specification:
+
+1. `license`
+2. `compatibility`
+3. `metadata`
+4. `allowed-tools`
+
+Claude Code-specific optional fields:
+
+1. `when_to_use`
+2. `argument-hint`
+3. `arguments`
+4. `disable-model-invocation`
+5. `user-invocable`
+6. `allowed-tools`
+7. `disallowed-tools`
+8. `model`
+9. `effort`
+10. `context`
+11. `agent`
+12. `hooks`
+13. `paths`
+14. `shell`
+
+Repository contract decisions:
+
+1. Treat `name` and `description` as required in all `SKILL.md` files.
+2. Keep Anthropic-facing semantics in standard fields.
+3. Keep MCP indexing metadata in a namespaced extension block.
+4. Preserve forward compatibility by allowing additive optional metadata fields over time.
+
+## Canonical Frontmatter Schema
+
+Use this two-layer pattern:
+
+1. Anthropic layer: top-level fields intended for Anthropic and Agent Skills behavior.
+2. Repository layer: one namespaced block, `x-personal-mcp`, for MCP catalog and routing metadata.
+
+Canonical shape:
+
+```yaml
+---
+name: <skill-id>
+description: <what this skill does and when to use it>
+
+# Optional Anthropic and Agent Skills fields
+when_to_use: <extra trigger guidance>
+allowed-tools: <space-separated string or YAML list>
+disable-model-invocation: false
+user-invocable: true
+license: <optional>
+compatibility: <optional>
+
+# Repository-specific metadata
+x-personal-mcp:
+  id: <skill-id>
+  version: <semver>
+  tags:
+    - <tag>
+  capabilities:
+    - resource://skills/<skill-id>/document
+  depends_on: []
+  references:
+    <ref-id>:
+      path: references/<file>.md
+      mime_type: text/markdown
+      title: <short title>
+---
+```
+
+## Repository Metadata Field Rules
+
+Rules for `x-personal-mcp`:
+
+1. `id` is required, must follow the skill id rules from the content contract, and must equal the directory name.
+2. `version` is required and must be a semantic version string.
+3. `tags` is optional and should be a list of kebab-case discovery labels.
+4. `capabilities` is required and lists the MCP URIs the skill publishes.
+5. `depends_on` is optional and lists other skill ids.
+6. `references` is an optional map keyed by `ref-id`.
+
+Reference entry rules:
+
+1. `ref-id` is lowercase kebab-case.
+2. `path` is a skill-relative markdown path and must stay inside the same skill directory.
+3. Nested folders under `references/` are allowed.
+4. `mime_type` defaults to `text/markdown` when omitted.
+5. `title` is an optional display label.
+6. Renaming `ref-id` values is allowed when needed; optional aliases may be used during transitions.
+
+## Validation Models
+
+The normative model uses Pydantic v2 with change-friendly validation:
+
+```python
+from __future__ import annotations
+
+import re
+from pathlib import PurePosixPath
+from typing import Any
+
+from pydantic import BaseModel, ConfigDict, Field, field_validator, model_validator
+
+SKILL_ID_RE = re.compile(r"^[a-z][a-z0-9-]*$")
+SEMVER_RE = re.compile(r"^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:[-+][0-9A-Za-z.-]+)?$")
+
+
+class ReferenceEntry(BaseModel):
+    model_config = ConfigDict(extra="ignore", str_strip_whitespace=True)
+
+    path: str
+    mime_type: str = "text/markdown"
+    title: str | None = None
+
+    @field_validator("path")
+    @classmethod
+    def validate_reference_path(cls, value: str) -> str:
+        p = PurePosixPath(value)
+        if p.is_absolute() or ".." in p.parts:
+            raise ValueError("reference path must be a relative in-skill path")
+        if not str(p).startswith("references/"):
+            raise ValueError("reference path must stay under references/")
+        if p.suffix.lower() != ".md":
+            raise ValueError("reference path must target a markdown file")
+        return str(p)
+
+
+class PersonalMcpMetadata(BaseModel):
+    model_config = ConfigDict(extra="ignore", str_strip_whitespace=True)
+
+    id: str
+    version: str
+    tags: list[str] = Field(default_factory=list)
+    capabilities: list[str] = Field(min_length=1)
+    depends_on: list[str] = Field(default_factory=list)
+    references: dict[str, ReferenceEntry] = Field(default_factory=dict)
+
+    @field_validator("id")
+    @classmethod
+    def validate_id(cls, value: str) -> str:
+        if not SKILL_ID_RE.fullmatch(value):
+            raise ValueError("id must be lowercase kebab-case and start with a letter")
+        return value
+
+    @field_validator("version")
+    @classmethod
+    def validate_version(cls, value: str) -> str:
+        if not SEMVER_RE.fullmatch(value):
+            raise ValueError("version must be semver")
+        return value
+
+    @field_validator("depends_on")
+    @classmethod
+    def validate_depends_on(cls, value: list[str]) -> list[str]:
+        for dep in value:
+            if not SKILL_ID_RE.fullmatch(dep):
+                raise ValueError(f"invalid depends_on skill id: {dep}")
+        return value
+
+    @field_validator("references")
+    @classmethod
+    def validate_reference_ids(cls, value: dict[str, ReferenceEntry]) -> dict[str, ReferenceEntry]:
+        for ref_id in value:
+            if not SKILL_ID_RE.fullmatch(ref_id):
+                raise ValueError(f"invalid reference id: {ref_id}")
+        return value
+
+    @model_validator(mode="after")
+    def ensure_primary_capability(self) -> "PersonalMcpMetadata":
+        expected = f"resource://skills/{self.id}/document"
+        if expected not in self.capabilities:
+            raise ValueError(f"capabilities must include {expected}")
+        return self
+
+
+class SkillFrontmatter(BaseModel):
+    model_config = ConfigDict(extra="ignore", str_strip_whitespace=True)
+
+    name: str = Field(min_length=1, max_length=64)
+    description: str = Field(min_length=1, max_length=1024)
+    when_to_use: str | None = None
+    allowed_tools: str | list[str] | None = Field(default=None, alias="allowed-tools")
+    disallowed_tools: str | list[str] | None = Field(default=None, alias="disallowed-tools")
+    disable_model_invocation: bool | None = Field(default=None, alias="disable-model-invocation")
+    user_invocable: bool | None = Field(default=None, alias="user-invocable")
+    argument_hint: str | None = Field(default=None, alias="argument-hint")
+    arguments: str | list[str] | None = None
+    license: str | None = None
+    compatibility: str | None = None
+    metadata: dict[str, str] | None = None
+
+    x_personal_mcp: PersonalMcpMetadata = Field(alias="x-personal-mcp")
+
+    @field_validator("name")
+    @classmethod
+    def validate_name(cls, value: str) -> str:
+        if not SKILL_ID_RE.fullmatch(value):
+            raise ValueError("name must be lowercase kebab-case and start with a letter")
+        if "anthropic" in value or "claude" in value:
+            raise ValueError("name must not contain reserved words anthropic or claude")
+        return value
+
+    @model_validator(mode="after")
+    def cross_validate(self) -> "SkillFrontmatter":
+        if self.x_personal_mcp.id != self.name:
+            raise ValueError("x-personal-mcp.id must exactly match name")
+        return self
+
+
+def validate_skill_frontmatter(raw: dict[str, Any], skill_dir_name: str) -> SkillFrontmatter:
+    model = SkillFrontmatter.model_validate(raw)
+    if model.name != skill_dir_name:
+        raise ValueError("frontmatter name must exactly match skill directory name")
+    return model
+```
+
+Validation behavior contract:
+
+1. Validate required core fields and relationships during registry load before FastMCP resource or tool registration.
+2. Allow unknown additive fields so frontmatter can evolve without blocking startup.
+3. Treat hard contract violations, including missing required fields, invalid ids, and broken required mappings, as startup errors.
+4. Treat non-critical compatibility issues as warnings when possible.
+5. Error messages should include the skill path and failing field for CI readability.
+
+Projection mode contract for Anthropic API upload pipelines:
+
+1. Parse with `SkillFrontmatter` first.
+2. Emit Anthropic-safe frontmatter with standard fields only.
+3. Serialize repository metadata into standard `metadata` as namespaced keys.
+4. Preserve the canonical authored source in `x-personal-mcp`; projection output is a build artifact.
+
+## Anthropic Upload Compatibility Rule
+
+1. Anthropic documentation guarantees behavior for standard frontmatter fields but does not explicitly guarantee handling of arbitrary unknown top-level keys.
+2. Publishing pipelines that target strict API compatibility should support a projection mode that emits only standard frontmatter fields for upload.
+3. In projection mode, repository extension metadata is serialized into the standard `metadata` field as namespaced keys or JSON-encoded values, while source-of-truth authoring remains in `x-personal-mcp`.
+
+## FastMCP Native Metadata Surfaces
+
+Resources support native definition metadata:
+
+1. `name`
+2. `description`
+3. `mime_type`
+4. `tags`
+5. `annotations`, including `readOnlyHint` and `idempotentHint`
+6. `icons`
+7. `meta`
+8. `version`
+9. `enabled`, which is deprecated in FastMCP v3 in favor of server-level enable and disable controls
+
+Resources also support runtime metadata through `ResourceContent.meta` and `ResourceResult.meta`.
+
+Tools support native definition metadata:
+
+1. `name`
+2. `description`
+3. `tags`
+4. `annotations`, including `title`, `readOnlyHint`, `destructiveHint`, `idempotentHint`, and `openWorldHint`
+5. `icons`
+6. `meta`
+7. `version`
+8. `timeout`
+9. `output_schema`
+10. `run_in_thread`
+11. `enabled`, which is deprecated in FastMCP v3 in favor of server-level enable and disable controls
+
+Tools also support runtime metadata through `ToolResult.meta`.
+
+## Frontmatter To FastMCP Mapping Contract
+
+At server startup, map `x-personal-mcp` into FastMCP registration as follows:
+
+1. `x-personal-mcp.id` defines the canonical URI namespace and identity checks.
+2. `description` becomes the default description for the primary skill document resource.
+3. `x-personal-mcp.tags` maps to resource and tool tags.
+4. `x-personal-mcp.version` maps to resource and tool version metadata.
+5. `x-personal-mcp.capabilities` becomes the registered URI list and catalog exposure.
+6. `x-personal-mcp.references[*]` becomes resource templates or concrete resources with `mime_type`, read-only annotations, and `meta` that includes `skill_id`, `ref_id`, and source `path`.
+7. `x-personal-mcp.depends_on` becomes catalog dependency graph metadata and validation inputs.
+
+## Invariants
+
+This contract guarantees:
+
+1. Anthropic-required frontmatter stays valid for custom skill upload and Claude Code loading.
+2. MCP-specific metadata remains embedded in `SKILL.md` frontmatter, with no `metadata.yaml` sidecar.
+3. FastMCP registration uses native metadata fields for resources and tools.
+4. Reference ids and metadata can evolve with low-friction updates while internal file layout under `references/` stays refactor-friendly.
+
+## Non-Goals
+
+This contract does not define:
+
+1. URI versioning and deprecation rollout policy details.
+2. Migration script design from existing `metadata.yaml` files.
+3. Runtime caching and indexing performance tuning.

docs/index.md

@@ -39,6 +39,9 @@ When the server is running, the health check is available at `/healthz` and the
 ## Architecture
 
 - [Resource-First Pattern Module Architecture](./architecture.md)
+- [Content Contract](./content.md)
+- [Frontmatter Contract](./frontmatter.md)
+- [URI Contract](./uris.md)
 - [Static Docs Hosting Pattern](./mcp_layout.md)
 - [Skill Usage Mechanics](./usage.md)
 - [Copilot MCP Mechanics](./copilot.md)

docs/mcp_contract_steps_1_5.md

@@ -1,66 +0,0 @@
-# FastMCP Greenfield Contracts (Steps 1-5)
-
-## Step 1: End-State Content Contract
-
-1. All authored markdown lives under docs/.
-2. Skill docs live under docs/skills/<skill-id>/.
-3. Canonical skill shape is:
-
-```text
-docs/
-  skills/
-    <skill-id>/
-      SKILL.md
-      references/
-```
-
-4. SKILL.md is required for every skill.
-5. references/ is the only place for skill-specific supporting docs.
-6. Skill directories are ownership boundaries.
-7. Skill id rules:
-   - lowercase kebab-case
-   - starts with a letter
-   - directory name matches skill id
-   - SKILL frontmatter id matches directory name
-
-## Step 2: SKILL Frontmatter and Metadata Contract
-
-1. name and description are required top-level frontmatter fields.
-2. Repository indexing metadata lives in x-personal-mcp.
-3. x-personal-mcp fields:
-   - required: id, version, capabilities
-   - optional: tags, depends_on, references
-4. references maps stable ref ids to skill-relative markdown paths under references/.
-5. metadata.yaml sidecars are not part of the canonical model.
-
-## Step 3: URI Contract and Compatibility Policy
-
-Canonical URI surface:
-
-1. resource://catalog/skills_index
-2. resource://catalog/skills/{skill_id}
-3. resource://skills/{skill_id}/document
-4. resource://skills/{skill_id}/references/{ref_id}
-5. resource://docs/{path*}
-
-Rules:
-
-1. skill_id and ref_id are lowercase kebab-case.
-2. docs path is markdown-only and cannot traverse outside docs/.
-3. URI families are unversioned and canonical in this phase.
-4. Breaking changes use direct replacement with no compatibility aliases.
-
-## Step 4: Docs Registry Loader Contract
-
-1. Loader uses importlib.resources.files(...) and Traversable APIs.
-2. Startup validates SKILL frontmatter schema, id invariants, reference integrity, dependency graph, and URI uniqueness.
-3. Registry is immutable for request-time reads.
-4. Invalid docs state is a hard startup error.
-
-## Step 5: Registry-Driven Resource Registration Contract
-
-1. FastMCP resources are registered from the validated registry.
-2. RFC6570 templates are used for parameterized routes.
-3. Docs resources declare explicit MIME types.
-4. Docs resources include readOnlyHint and idempotentHint annotations.
-5. Duplicate registrations fail startup via strict duplicate policy.

docs/mcp_layout.md

@@ -29,8 +29,10 @@ treeView-beta
       "docs"
          "index.md"
          "architecture.md"
+         "content.md"
+         "frontmatter.md"
          "mcp_layout.md"
-         "mcp_contract_steps_1_5.md"
+         "uris.md"
          "skills"
             "new-skill"
                "SKILL.md"
@@ -153,8 +155,6 @@ When clients cannot attach MCP resources directly, thin catalog tools may retrie
 
 ## URI Compatibility Policy
 
-This phase is a greenfield break-and-replace baseline.
-
 1. Canonical URIs are the only supported URIs in this runtime.
 2. No backward-compatibility aliases or dual registration paths are maintained.
 3. Contract changes should update clients to canonical URIs directly.

docs/new_skill.md

@@ -1,8 +1,10 @@
 # Hooking Up a New Skill
 
-Use this checklist to add a new skill in the Phase 1 docs-first model.
+Use this checklist to add a new skill in the docs-first model.
 
-## Step 1 Contract: Canonical Skill Shape
+For the full contract details, see [Content Contract](./content.md), [Frontmatter Contract](./frontmatter.md), and [URI Contract](./uris.md).
+
+## Canonical Skill Shape
 
 Create one skill directory under `docs/skills/`:
 
@@ -22,7 +24,7 @@ Rules:
 3. Skill directories are ownership boundaries; no cross-skill writes.
 4. `skill-id` is lowercase kebab-case and should remain stable.
 
-## Step 2 Contract: SKILL.md Frontmatter
+## SKILL.md Frontmatter
 
 `SKILL.md` frontmatter is authoritative for metadata.
 
@@ -74,7 +76,7 @@ Reference manifest rules:
 
 No `metadata.yaml` sidecar is part of this model.
 
-## Step 3 Contract: URI Surface
+## URI Surface
 
 Canonical resource URIs for a skill:
 

docs/uris.md

@@ -0,0 +1,114 @@
+# URI Contract
+
+This page defines the canonical resource URI contract, template parameter rules, and compatibility policy.
+
+## Canonical URI Surface
+
+The public, preferred URIs are:
+
+1. `resource://catalog/skills_index`
+2. `resource://catalog/skills/{skill_id}`
+3. `resource://skills/{skill_id}/document`
+4. `resource://skills/{skill_id}/references/{ref_id}`
+5. `resource://docs/{path*}`
+
+Contract intent:
+
+1. Catalog URIs are discovery surfaces.
+2. Skill URIs are the primary per-skill guidance surfaces.
+3. The docs wildcard URI is a direct authored-markdown access surface under `docs/`.
+
+## URI Semantics
+
+### `resource://catalog/skills_index`
+
+1. Returns a compact list of skill records for discovery.
+2. Contains one entry per `skill_id`.
+3. Includes enough metadata for client-side selection, at minimum `id`, `name`, `description`, `tags`, and `capabilities`.
+
+### `resource://catalog/skills/{skill_id}`
+
+1. Returns one normalized record for `skill_id`.
+2. Includes the canonical document URI and declared reference ids.
+3. Returns not found when `skill_id` does not exist.
+
+### `resource://skills/{skill_id}/document`
+
+1. Returns the canonical `SKILL.md` authored content for that skill.
+2. `skill_id` must satisfy the stable skill id rules from the content contract.
+
+### `resource://skills/{skill_id}/references/{ref_id}`
+
+1. Returns one reference document declared in the skill frontmatter references manifest.
+2. `ref_id` is the stable public handle for that reference document.
+
+### `resource://docs/{path*}`
+
+1. Returns authored markdown at a normalized relative path under `docs/`.
+2. Supports nested paths via RFC6570 wildcard expansion.
+3. Typical examples include `index.md`, `usage.md`, `skills/<skill-id>/SKILL.md`, and `skills/<skill-id>/references/<file>.md`.
+
+## Template Parameter And Validation Rules
+
+### `skill_id`
+
+1. Lowercase kebab-case.
+2. Must satisfy the stable skill id rules from the content contract.
+
+### `ref_id`
+
+1. Lowercase kebab-case.
+2. Must be declared in the skill's references manifest.
+
+### `path*`
+
+1. Relative POSIX path only.
+2. No leading slash.
+3. No `..` traversal segments.
+4. Resolves only inside `docs/`.
+5. Markdown-only in the end state, meaning `.md` files.
+
+## URI Versioning Policy
+
+Default rule:
+
+1. Keep URIs unversioned by default.
+2. Allow URI and payload updates when they improve clarity or implementation simplicity.
+
+Breaking-change rule:
+
+1. Breaking changes use direct replacement of the canonical URI family.
+2. No compatibility aliases or dual URI families are maintained.
+
+FastMCP version metadata usage:
+
+1. Resource `version` metadata may be used for implementation and version discovery.
+2. URI readability and maintainability remain the primary contract.
+
+## Reference Id Compatibility Policy
+
+`ref_id` is the public identifier for a reference document, separate from file path.
+
+Rules:
+
+1. Prefer keeping `ref_id` stable when practical.
+2. File paths may change without URI churn as long as the mapped `ref_id` still resolves.
+3. If a reference is renamed, introduce a new `ref_id` and treat the old one as retired.
+4. Avoid reusing retired `ref_id` values for unrelated content.
+
+## Invariants
+
+This contract guarantees:
+
+1. One canonical URI pattern per core capability surface.
+2. Fast, low-friction URI evolution through direct replacement of canonical URIs.
+3. A single canonical catalog URI family with no alias maintenance overhead.
+4. Reference mappings can evolve with minimal churn.
+
+## Non-Goals
+
+This contract does not define:
+
+1. Implementation-specific transform wiring details, such as `VersionFilter`, mounts, or provider composition.
+2. Migration script mechanics for auto-generating aliases.
+3. Authorization policy design for URI-level access control.

zensical.toml

@@ -48,9 +48,11 @@ nav = [
   { "Home" = "index.md" },
   { "Guide" = [
     { "Arch" = "architecture.md" },
+    { "Content" = "content.md" },
+    { "Frontmatter" = "frontmatter.md" },
+    { "URIs" = "uris.md" },
     { "MCP" = "mcp_layout.md" },
     { "Copilot" = "copilot.md" },
-    { "Contracts 1-5" = "mcp_contract_steps_1_5.md" },
     { "Usage" = "usage.md" },
     { "Future Work" = "future_work.md" },
     { "New Skill" = "new_skill.md" },