Zap XML Generation

ZAP XML Generation from Spec to SDK (Alchemy)

This skill provides comprehensive instructions, scenarios, and commands for generating and amending ZAP template XML files (.xml) in the Matter SDK repository (connectedhomeip) from Matter specification AsciiDoc documents (.adoc) using Alchemy (alchemy zap).

1. Overview & Tool Setup

Alchemy is the canonical command-line tool for transforming Matter specification documents into code-generation artifacts. When invoked with the zap subcommand, Alchemy parses the AsciiDoc data model definitions and translates them into the ZAP XML files located in the Matter SDK under src/app/zap-templates/zcl/data-model/chip/.

1.1 Obtaining & Building Alchemy in alchemy Folder

Always clone and build Alchemy inside its own dedicated alchemy folder (for example, as a sibling directory ../alchemy), rather than inside the connectedhomeip repository:

# Clone and build inside a dedicated alchemy folder alongside your SDK/Spec clones
git clone https://github.com/project-chip/alchemy.git ../alchemy
cd ../alchemy
go build -o alchemy .

Alternatively, prebuilt binaries can be downloaded directly from the Alchemy GitHub releases page.

1.2 Standard Repository Paths & Execution Context

When executing commands, assume you are running from inside the root directory of the Matter SDK repository (connectedhomeip) and invoking the binary built in the alchemy folder (../alchemy/alchemy, or alchemy if installed to your $PATH):

cd <path_to_connectedhomeip>
../alchemy/alchemy zap --sdk-root=. --spec-root=../connectedhomeip-spec [options] [spec_doc_paths...]

• Current Working Directory (CWD): connectedhomeip (.)
• Alchemy Binary Location: ../alchemy/alchemy (built in alchemy folder)
• SDK Root (--sdk-root): . (the current working directory)
• Specification Root (--spec-root): ../connectedhomeip-spec (assuming a sibling clone of connectedhomeip-spec)
• Output Location in SDK: src/app/zap-templates/zcl/data-model/chip/

2. Core Generation Scenarios

2.1 Scenario 1: Amending an Existing Cluster (-cluster.xml)

Use Case: You modified, added, or removed attributes, commands, events, or data types in an existing cluster AsciiDoc file (connectedhomeip-spec/src/app_clusters/<ClusterName>.adoc) and need to update its corresponding XML in the SDK (<cluster-name>-cluster.xml).

alchemy zap --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/Thermostat.adoc

Key Behaviors & Gotchas:

• Amending by Default: Alchemy reads the existing XML file and amends it. It preserves element order, existing comments, and unrecognized XML attributes while injecting or updating spec entities.
• Automatic Dependency Tracking: If the target cluster relies on data types (structs, bitmaps, enums) defined in other cluster docs or global data types (global-structs.xml, global-enums.xml), Alchemy automatically generates/amends those dependency XMLs as well.
• Index & List Updates: Alchemy automatically registers any updates in src/app/zap-templates/zcl/data-model/chip/clusters.xml and src/app/zap-templates/zcl/zcl.json.

2.2 Scenario 2: Generating XML for a New / Provisional Cluster

Use Case: A new cluster AsciiDoc document was introduced in connectedhomeip-spec and does not yet have an XML template in the SDK.

alchemy zap --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/NewAwesomeCluster.adoc

Key Behaviors:

• Alchemy detects that <cluster-name>-cluster.xml does not exist and creates a new XML file from scratch with standard XML headers and copyright/license comments.
• The new cluster is automatically added to clusters.xml, zcl.json, and provisional index files (provisional.xml / index.xml as applicable).

2.3 Scenario 3: Generating XML for Features Behind Conditional #ifdef Attributes

Use Case: A cluster, attribute, or feature in the specification is wrapped in an AsciiDoc ifdef block (e.g., guarded by in-progress or a specific feature flag like my-cool-feature).

ifdef::in-progress,my-cool-feature[]
include::./MyAwesomeCluster.adoc[]
endif::[]

Command:

alchemy zap --attribute="in-progress" --attribute="my-cool-feature" --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/MyAwesomeCluster.adoc

[!IMPORTANT] > Why --attribute is Mandatory: Alchemy generates ZAP XML strictly based on what renders in the AsciiDoc document during processing. If a feature or cluster is hidden by an ifdef::in-progress[] condition and you do not pass --attribute="in-progress", Alchemy will treat those entities as non-existent and will omit or delete them from the generated XML!

2.4 Scenario 4: Applying Provisional API Maturity Policies (--provisional-policy)

Use Case: Controlling how apiMaturity="provisional" XML attributes are assigned to generated data types (Clusters, Attributes, Commands, Enums, Structs, Bitmaps, Events) depending on their draft status in the specification.

alchemy zap --provisional-policy=loose --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/Thermostat.adoc

Available Policies:

• none (Default):
  • Clusters and attributes with provisional conformance in the spec are written with apiMaturity="provisional".
  • If they do not have provisional conformance, apiMaturity is removed if it previously existed.
  • Structs that do not currently exist in the ZAP XML are written with apiMaturity="provisional".
• loose:
  • Writes or clears apiMaturity="provisional" on all entity types (Attributes, Bitmaps, Clusters, Commands, Enums, Events, Features, Structs, and Fields).
  • Entities are considered provisional unless they have a non-provisional conformance column OR are referenced by a non-provisional data type.
• strict:
  • Follows the same rules as loose, but refuses to add new data types to the generated XML if they are not provisional in the spec. Use this policy when enforcing strict API stability gates.

2.5 Scenario 5: Updating Device Types and Namespaces

Use Case: You modified Device Type definitions (connectedhomeip-spec/src/device_types/*.adoc) or Namespace definitions (connectedhomeip-spec/src/namespaces/*.adoc).

[!WARNING] > Device Types Support Limitation: Note that automatic generation and patching of device-types.xml from AsciiDoc documents is currently not fully supported in Alchemy. While the command exists and attempts basic patching, output may be incomplete or experimental. Always manually inspect and verify any changes to device-types.xml.

# Update Device Types (experimental / not fully supported - modifies device-types.xml)
alchemy zap --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/device_types/*.adoc

# Update Namespaces (modifies src/app/zap-templates/zcl/data-model/chip/namespaces.xml)
alchemy zap --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/namespaces/*.adoc

Key Behaviors:

• Namespace .adoc files map collectively to namespaces.xml.
• Device type .adoc files map collectively to device-types.xml (configurator/deviceType elements), but note the partial support limitation above.

2.6 Scenario 6: Whole-Spec and Batch Processing

Use Case: Regenerating or updating ZAP XMLs across the entire specification (e.g., during major SDK-Spec synchronizations).

alchemy zap --sdk-root=. --spec-root=../connectedhomeip-spec

(When no specific .adoc files are passed, Alchemy parses all documents discovered in --spec-root and updates all corresponding SDK XML files).

3. Error Mitigation & Validation Scenarios

If the specification has syntax errors or missing dependencies, Alchemy will halt with a fatal error: Alchemy was unable to proceed due to the following fatal errors in parsing the spec

Use the following strategies based on your workflow needs:

3.1 Exclude Specific Errored Files (--exclude)

If a few unrelated spec documents fail to parse while you are generating XMLs for a different cluster, exclude the broken paths:

alchemy zap --sdk-root=. --spec-root=../connectedhomeip-spec --exclude="*/BrokenCluster.adoc" ../connectedhomeip-spec/src/app_clusters/*.adoc

(The --exclude flag supports glob patterns and can be passed multiple times).

3.2 Automatically Ignore Errored Files (--ignore-errored)

To automatically skip any spec file that encounters parsing errors while generating XML for all valid files:

alchemy zap --ignore-errored --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/*.adoc

3.3 Force Generation Despite Errors (--force)

Forces Alchemy to generate XML files on a best-effort basis even when parsing errors occur:

alchemy zap --force --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/*.adoc

[!WARNING] Use --force only as a last resort for local debugging. Best-effort generation from partially parsed AsciiDoc files can produce incomplete or corrupted XML structures. Always prefer fixing the underlying specification error or using --exclude.

4. Preview & Verification Scenarios

4.1 Dry Run (--dry-run / -d)

Run all AsciiDoc parsing, dependency resolution, and XML rendering logic without writing any files to disk. Useful for verifying that your spec changes parse cleanly:

alchemy zap --dry-run --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/Thermostat.adoc

4.2 Patch Output (--patch / -p)

Generate a unified diff (.patch) to stdout showing the exact XML additions, modifications, and deletions without modifying the SDK directly:

alchemy zap --patch --sdk-root=. --spec-root=../connectedhomeip-spec ../connectedhomeip-spec/src/app_clusters/Thermostat.adoc > zap_changes.patch

5. Summary Cheatsheet