docs: migrate remaining content into documentation site

Fill all stub pages with content from existing docs:
- Language: microflows, pages, security, navigation, workflows,
  business events (31 pages)
- Tools: code navigation, catalog, linting, testing, external SQL,
  Docker integration (32 pages)
- IDE: VS Code extension, LSP server, mxcli init (14 pages)
- Go Library: remaining API methods, builders, examples (6 pages)
- Internals: MPR format, widget templates, catalog schema,
  design decisions, adding statements (10 pages)
- Appendixes: glossary, SDK equivalence, version compatibility,
  error messages, changelog (5 pages)

Only tutorial pages (Part I) and reference category READMEs remain
as stubs — tutorial content needs to be written from scratch.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ako

docs-site/src/appendixes/changelog.md

@@ -1,3 +1,23 @@
 # Changelog
 
 Version history and release notes for ModelSDK Go and the mxcli tool.
+
+## Releases
+
+See [GitHub Releases](https://github.com/mendixlabs/mxcli/releases) for the complete version history, including:
+
+- Release notes with feature descriptions
+- Pre-built binaries for all platforms (Linux, macOS, Windows -- amd64 and arm64)
+- Source code archives
+
+## Versioning
+
+mxcli follows [Semantic Versioning](https://semver.org/):
+
+- **Major** -- breaking changes to the MDL language or Go library API
+- **Minor** -- new features and capabilities (backward-compatible)
+- **Patch** -- bug fixes and documentation updates
+
+## Status
+
+> **Alpha-quality software.** This project is in early stages. Expect bugs, missing features, and rough edges. Always back up your Mendix project files before using mxcli to modify them.

docs-site/src/appendixes/error-messages.md

@@ -1,3 +1,148 @@
 # Error Messages Reference
 
-Index of error messages produced by mxcli, the MDL parser, and the SDK, with explanations and suggested solutions.
+Common error messages from Studio Pro, mxcli, and the MDL parser, with explanations and solutions.
+
+## Studio Pro Errors
+
+These errors appear when opening a project in Studio Pro after modification by mxcli.
+
+### TypeCacheUnknownTypeException
+
+```
+TypeCacheUnknownTypeException: The type cache does not contain a type
+with qualified name DomainModels$Index
+```
+
+**Cause:** The BSON `$Type` field uses the **qualifiedName** instead of the **storageName**. These are often identical, but not always.
+
+**Solution:** Check the metamodel reflection data for the correct storage name:
+
+| qualifiedName (wrong) | storageName (correct) |
+|-----------------------|----------------------|
+| `DomainModels$Entity` | `DomainModels$EntityImpl` |
+| `DomainModels$Index` | `DomainModels$EntityIndex` |
+
+Look up the type in `reference/mendixmodellib/reflection-data/<version>-structures.json` and use the `storageName` field value.
+
+### CE0463: Widget definition changed
+
+```
+CE0463: The widget definition of 'DataGrid2' has changed.
+```
+
+**Cause:** The widget's `WidgetObject` properties do not match its `PropertyTypes` schema. This happens when:
+
+- A widget template is missing properties
+- Property values have incorrect types
+- The template was extracted from a different Mendix version
+
+**Solution:**
+1. Create the same widget manually in Studio Pro
+2. Extract its BSON from the saved project
+3. Compare the template's `object` section against the Studio Pro version
+4. Update `sdk/widgets/templates/<version>/<Widget>.json` to match
+
+See the debug workflow in `.claude/skills/debug-bson.md` for step-by-step instructions.
+
+### CE0066: Entity access is out of date
+
+```
+CE0066: Entity access for 'MyModule.Customer' is out of date.
+```
+
+**Cause:** Association MemberAccess entries were added to the wrong entity. In Mendix, association access rules must only be on the **FROM** entity (the one stored in `ParentPointer`), not the TO entity.
+
+**Solution:** Ensure `MemberAccess` entries for associations are added only to the entity that owns the foreign key (the FROM side of the association). Remove any association MemberAccess entries from the TO entity.
+
+### System.ArgumentNullException (ValidationRule)
+
+```
+System.ArgumentNullException: Value cannot be null.
+```
+
+**Cause:** A validation rule's `Attribute` field uses a binary UUID instead of a qualified name string. The metamodel specifies `BY_NAME_REFERENCE` for this field.
+
+**Solution:** Use a qualified name string (e.g., `"Module.Entity.Attribute"`) for the `Attribute` field in ValidationRule BSON, not a binary UUID.
+
+## mxcli Parser Errors
+
+### Mismatched input
+
+```
+Line 3, Col 42: mismatched input ')' expecting ','
+```
+
+**Cause:** Syntax error in the MDL statement -- typically a missing comma, semicolon, or unmatched bracket.
+
+**Solution:** Check the MDL syntax at the reported line and column. Common issues:
+- Missing commas between attribute definitions
+- Missing semicolons at the end of statements
+- Unmatched parentheses or curly braces
+
+### No viable alternative
+
+```
+Line 1, Col 0: no viable alternative at input 'CREAT'
+```
+
+**Cause:** Unrecognized keyword or misspelling.
+
+**Solution:** Check the keyword spelling. MDL keywords are case-insensitive but must be valid. Run `mxcli syntax keywords` for the full keyword list.
+
+## mxcli Execution Errors
+
+### Module not found
+
+```
+Error: module 'MyModule' not found in project
+```
+
+**Cause:** The referenced module does not exist in the `.mpr` file.
+
+**Solution:** Check the module name with `SHOW MODULES` and verify the spelling. Module names are case-sensitive.
+
+### Entity not found
+
+```
+Error: entity 'MyModule.Customer' not found
+```
+
+**Cause:** The referenced entity does not exist in the specified module.
+
+**Solution:** Check with `SHOW ENTITIES IN MyModule`. If the entity was just created, ensure the create statement executed successfully before referencing it.
+
+### Reference validation failed
+
+```
+Error: unresolved reference 'MyModule.NonExistent' at line 5
+```
+
+**Cause:** A qualified name references an element that does not exist in the project. This error appears with `mxcli check script.mdl -p app.mpr --references`.
+
+**Solution:** Verify the referenced element exists, or create it before the referencing statement.
+
+## BSON Serialization Errors
+
+### Wrong array prefix
+
+**Symptom:** Studio Pro fails to load the project or shows garbled data.
+
+**Cause:** Missing or incorrect integer prefix in BSON arrays. Mendix BSON arrays require a count/type prefix as the first element:
+
+```json
+{
+  "Attributes": [3, { ... }, { ... }]
+}
+```
+
+**Solution:** Ensure all arrays include the correct prefix value (typically `2` or `3`). Check existing BSON output for the correct prefix for each array property.
+
+### Wrong reference format
+
+**Symptom:** Studio Pro crashes or shows null reference errors.
+
+**Cause:** Using `BY_ID_REFERENCE` (binary UUID) where `BY_NAME_REFERENCE` (qualified string) is expected, or vice versa.
+
+**Solution:** Check the metamodel reflection data for the property's `kind` field:
+- `BY_ID_REFERENCE` -> use binary UUID
+- `BY_NAME_REFERENCE` -> use qualified name string (e.g., `"Module.Entity.Attribute"`)

docs-site/src/appendixes/glossary.md

@@ -1,3 +1,130 @@
 # Glossary
 
-Mendix-specific terms and concepts explained for developers who are new to the Mendix platform.
+Mendix-specific terms and concepts for developers who are new to the Mendix platform.
+
+## A
+
+**Association**
+A relationship between two entities. Analogous to a foreign key in relational databases. Mendix supports `Reference` (one-to-many or one-to-one) and `ReferenceSet` (many-to-many) types.
+
+**Attribute**
+A property of an entity. Equivalent to a column in a relational database table. Types include String, Integer, Long, Decimal, Boolean, DateTime, AutoNumber, Binary, Enumeration, and HashedString.
+
+**Access Rule**
+A security rule that controls which module roles can create, read, write, or delete instances of an entity, and which attributes they can access.
+
+## B
+
+**BSON**
+Binary JSON. The serialization format Mendix uses to store model elements inside MPR files. Each document (entity, microflow, page, etc.) is stored as a BSON blob.
+
+**Building Block**
+A reusable page fragment that can be dragged onto pages in Studio Pro. Similar to a Snippet but intended for the toolbox.
+
+## C
+
+**Catalog**
+In mxcli, an in-memory SQLite database that indexes project metadata for fast querying, full-text search, and cross-reference navigation.
+
+**Constant**
+A named value defined at the module level that can be configured per environment (development, acceptance, production). Used for API keys, URLs, feature flags, etc.
+
+## D
+
+**DataGrid**
+A widget that displays a list of objects in a tabular format with columns, sorting, and search. The classic DataGrid uses server-side rendering; DataGrid2 is the pluggable widget version.
+
+**DataView**
+A widget that displays a single object, providing a context for input widgets (TextBox, DatePicker, etc.) to read and write attributes.
+
+**Domain Model**
+The data model for a module, consisting of entities, their attributes, and associations between them. Analogous to an entity-relationship diagram.
+
+## E
+
+**Entity**
+A data type in the domain model. Equivalent to a table in a relational database. Entities can be persistent (stored in the database), non-persistent (in-memory only), or view (backed by an OQL query).
+
+**Enumeration**
+A fixed set of named values (e.g., OrderStatus with values Draft, Active, Closed). Used as attribute types when the set of possible values is known at design time.
+
+**Event Handler**
+Logic that runs automatically before or after a commit or delete operation on an entity. Configured on the entity in the domain model.
+
+## G
+
+**Gallery**
+A pluggable widget that displays a list of objects in a card/tile layout, as opposed to the tabular layout of a DataGrid.
+
+**Generalization**
+Entity inheritance. When entity B generalizes entity A, B inherits all of A's attributes and associations. Analogous to class inheritance in object-oriented programming.
+
+## L
+
+**Layout**
+A page template that defines the common structure (header, sidebar, footer) shared by multiple pages. Every page references a layout.
+
+**LayoutGrid**
+A responsive grid widget based on a 12-column system. Used to create multi-column layouts with breakpoints for phone, tablet, and desktop.
+
+## M
+
+**MDL (Mendix Definition Language)**
+A SQL-like text language for querying and modifying Mendix projects. The primary interface for mxcli.
+
+**Microflow**
+Server-side logic expressed as a visual flow of activities. Microflows can retrieve data, call actions, make decisions, loop over lists, and return values. They run on the Mendix runtime (server).
+
+**Module**
+A top-level organizational unit in a Mendix project. Each module contains its own domain model, microflows, pages, enumerations, and security settings. Analogous to a package or namespace.
+
+**Module Role**
+A permission role defined within a module. Module roles are assigned to user roles at the project level. Entity access rules, microflow access, and page access are granted to module roles.
+
+**MPR**
+Mendix Project Resource file. The binary file (`.mpr`) that contains the complete Mendix project model. It is a SQLite database with BSON-encoded documents.
+
+## N
+
+**Nanoflow**
+Client-side logic that runs in the browser (or native app). Syntactically similar to microflows but with restrictions (no database transactions, limited activity types). Used for offline-capable and low-latency operations.
+
+## P
+
+**Page**
+A user interface screen in a Mendix application. Pages contain widgets (TextBox, DataGrid, Button, etc.) and reference a layout for their outer structure.
+
+**Pluggable Widget**
+A widget built with the Mendix Pluggable Widget API (React-based). Examples: DataGrid2, ComboBox, Gallery. Pluggable widgets use JSON-based property schemas (PropertyTypes) stored in the MPR.
+
+## R
+
+**Runtime**
+The Mendix server-side execution environment (Java-based) that runs the application. It interprets the model, handles HTTP requests, executes microflows, and manages the database.
+
+## S
+
+**Scheduled Event**
+A microflow that runs automatically on a timer (e.g., every hour, daily at midnight). Configured with a start time and interval.
+
+**Snippet**
+A reusable UI fragment that can be embedded in multiple pages via a SnippetCall widget. Snippets can accept parameters.
+
+**Studio Pro**
+The visual IDE for building Mendix applications. It reads and writes `.mpr` files. mxcli provides a complementary text-based interface to the same project files.
+
+**Storage Name**
+The internal type identifier used in BSON `$Type` fields. Often the same as the qualified name, but not always (e.g., `DomainModels$EntityImpl` is the storage name for `DomainModels$Entity`).
+
+## U
+
+**User Role**
+A project-level role that aggregates module roles from one or more modules. End users are assigned user roles, which determine their permissions across the entire application.
+
+## W
+
+**Widget**
+A UI component on a page. Built-in widgets include TextBox, DataGrid, Button, Container, and LayoutGrid. Pluggable widgets extend this set with third-party components.
+
+**Workflow**
+A long-running process with user tasks, decisions, and parallel paths. Workflows model approval processes, multi-step procedures, and human-in-the-loop automation.