Managing Change Data Capture Enablement

Generate the metadata that subscribes Salesforce objects to Change Data Capture: PlatformEventChannelMember files for the default ChangeEvents channel or a custom channel, and PlatformEventChannel files for new custom channels. Covers enrichment fields, filter expressions, and the canonical naming and value formats that the Metadata API actually accepts (which differ from values that appear in many internal test fixtures and code-search hits).

Scope

• In scope: Generating PlatformEventChannelMember and PlatformEventChannel metadata for CDC. Subscribing standard objects, custom objects, or both. Configuring enrichment fields. Configuring filter expressions. Defining custom data channels.
• Out of scope: Publishing custom platform events (PE) — that's a different metadata type (PlatformEvent). Pub/Sub API or external Kafka/Bayeux configuration. Pricing/limits guidance — refer the user to the CDC Developer Guide. Programmatic event-bus subscribers in Apex.

---

Clarifying Questions

Before generating, confirm with the user if not already clear:

• Which entity (or entities) need CDC enablement? Standard, custom, or both?
• Default channel (ChangeEvents) or a custom channel? If custom, what's the channel label?
• Any enrichment fields needed? (Lookup IDs that the consumer needs even when they didn't change.)
• Any filter expression needed? (A SOQL-WHERE-clause body that gates which change events emit.)

---

Required Inputs

Gather or infer before proceeding:

• Source entity API name(s) — e.g. Account, Lead, Order__c. The skill internally translates this to the ChangeEvent entity name (see Workflow step 2).
• Channel — either ChangeEvents (default) or the developer name of a custom channel ending in __chn.
• Enrichment fields (optional) — list of field API names on the source object whose values should be included in every change event.
• Filter expression (optional) — a predicate over fields on the change event payload (e.g. Status__c != null).

Defaults unless specified:

• Channel: ChangeEvents (the default CDC channel — no path prefix).
• Enrichment fields: none.
• Filter expression: none.

If the user provides a clear, complete request, generate immediately without unnecessary back-and-forth.

---

Workflow

All steps are sequential. Do not skip or reorder.

Before generating anything, know the only valid CDC metadata types: CDC is expressed entirely through PlatformEventChannelMember (one per subscribed entity) and PlatformEventChannel (only for custom channels). Do NOT use <ChangeDataCapture>, .changeDataCapture-meta.xml, changeDataCapture/ directories, EnableChangeDataCapture, or ManagedEventSubscription — these are not in scope for CDC. If you find yourself writing any of them, stop and use a PlatformEventChannelMember file instead.

1. Identify the channel — if the user names a custom channel, you'll generate a PlatformEventChannel file (see step 4). Otherwise use the literal value ChangeEvents for the default channel.

2. Translate source entity to ChangeEvent entity name — <selectedEntity> is the ChangeEvent type, NOT the source object:

   Source object	<selectedEntity> value
   Account	AccountChangeEvent
   Lead	LeadChangeEvent
   Contact	ContactChangeEvent
   Order__c (custom)	Order__ChangeEvent
   MyThing__c (custom)	MyThing__ChangeEvent

   For standard objects: append ChangeEvent. For custom objects: replace the trailing __c with __ChangeEvent (the double-underscore is preserved).

3. Generate the channel-member file — one file per (entity, channel) pair. The filename and fullName always use a SINGLE underscore between the entity stem and ChangeEvent — this is independent of how selectedEntity is formatted in the XML body. For custom objects, drop the __c from the source name when forming the filename:

   Source object	Filename (and fullName)	<selectedEntity> (in XML)
   Account	Account_ChangeEvent.platformEventChannelMember-meta.xml	AccountChangeEvent
   Lead	Lead_ChangeEvent.platformEventChannelMember-meta.xml	LeadChangeEvent
   Order__c	Order_ChangeEvent.platformEventChannelMember-meta.xml (NOT Order__ChangeEvent)	Order__ChangeEvent
   MyThing__c	MyThing_ChangeEvent.platformEventChannelMember-meta.xml (NOT MyThing__ChangeEvent)	MyThing__ChangeEvent

   The custom-object case is the easiest place to slip — the filename uses single underscore, the selectedEntity keeps its double underscore. Read assets/PlatformEventChannelMember-template.xml as the structural template.

4. For a custom channel, generate a PlatformEventChannel file — required if any member references a non-default channel. Derive a DeveloperName from the user's label: strip spaces and non-alphanumeric characters, convert to CamelCase, then always append the literal suffix __chn. The filename and the channel's <eventChannel> reference must use this exact form, otherwise the deploy fails with Invalid channel name:

   User says	DeveloperName	Filename
   Partner Sync	PartnerSync__chn	PartnerSync__chn.platformEventChannel-meta.xml (NOT Partner_Sync... or PartnerSync...)
   Order Updates	OrderUpdates__chn	OrderUpdates__chn.platformEventChannel-meta.xml
   data sync	DataSync__chn	DataSync__chn.platformEventChannel-meta.xml

   Members on this channel reference it by the same DeveloperName: <eventChannel>PartnerSync__chn</eventChannel>. Read assets/PlatformEventChannel-template.xml.

5. Add enrichment fields if requested — repeat the <enrichedFields><name>FIELD_API_NAME</name></enrichedFields> block for each field. The name must be a single-hop API name on the source entity — verified working with: standard lookup IDs (OwnerId, ParentId), custom lookup fields (MyLookup__c), and custom non-relationship fields (Region__c, Status__c). Relationship traversals like Owner.Name or Parent.Account.Industry are rejected by deploy with "The selected field, X.Y, isn't valid".

6. Add a filter expression if requested — wrap the predicate in <filterExpression>...</filterExpression>. The body is a WHERE-clause body without the WHERE keyword (e.g. Status__c != null, not WHERE Status__c != null). For supported operators, field types, and pitfalls, read references/filter-expressions.md.

---

Rules / Constraints

Constraint	Rationale
<selectedEntity> is the ChangeEvent type name, not the source object name	The Metadata API binds the member to a ChangeEvent entity — passing Account directly fails with "invalid event in selectedEntity".
Member fullName uses single underscore: Account_ChangeEvent	The double-underscore form (Account__ChangeEvent) is parsed as <namespace>__<name> and rejected: "Cannot create a new component with the namespace: Account".
Default channel value is exactly ChangeEvents — no path prefix	Older fixtures and some docs show data/ChangeEvents; the deploy returns "Unable to find the specified channel" for that value.
Enrichment field names are single-hop API names on the source entity	Standard (OwnerId), custom lookup (MyLookup__c), and custom non-relationship (Region__c) all validate. Traversals like Owner.Name are rejected: "The selected field, X.Y, isn't valid".
<filterExpression> body has no WHERE keyword	Deploy returns "filter expression has syntax errors: unexpected token: 'WHERE'".
Filter cannot reference IsDeleted or do relationship traversal (Owner.Username)	Deploy rejects with "field is invalid".
DateTime fields support only equality in filters (=, !=) — not < / >	Deploy returns "Only equality operators are supported for this field type or value". Use a named date literal: LastModifiedDate = TODAY.
Filter RHS must be a literal — no field-to-field comparison	BillingCity = ShippingCity returns "unexpected token: 'ShippingCity'".
Compound fields (e.g. BillingAddress) require dotted component access in filter	BillingAddress.City = 'X' deploys; flat BillingCity is rejected as "field is invalid"; raw BillingAddress is rejected as "has to be used with a component field". Note this is the OPPOSITE of <enrichedFields>, which uses flat names.
Custom channel filename ends with __chn before the meta-xml suffix	Salesforce's MDAPI naming convention; mismatch causes deploy ambiguity.
Custom channel XML must include <channelType>data</channelType>	Without data, the channel is rejected for CDC (other types exist for streaming/event channels).
Source custom objects must already exist (or be deployed in the same transaction)	The ChangeEvent entity for Foo__c doesn't exist until Foo__c does; member deploy fails otherwise.
Never generate a PlatformEventChannel file for the default ChangeEvents channel	The default channel is system-provided. Reference it via <eventChannel>ChangeEvents</eventChannel> on members, but only custom (__chn) channels need a channel-meta file.
PlatformEventChannelMember accepts ONLY four elements: <enrichedFields>, <eventChannel>, <filterExpression>, <selectedEntity>	Adding <description>, <isActive>, <masterLabel>, or any other element fails XML schema validation: "Element {...} invalid at this location". Stick to the four documented elements.
PlatformEventChannel accepts ONLY two elements: <channelType> and <label>	Adding <masterLabel>, <description>, etc. produces "Element {...}masterLabel invalid at this location in type PlatformEventChannel". Use <label>, not <masterLabel>.
Generated metadata files only — never run sf project deploy start from this skill	This skill produces artifacts; deployment is a separate lifecycle concern.

---

Gotchas

Issue	Resolution
Unable to find the specified channel	Set <eventChannel>ChangeEvents</eventChannel> (no data/ prefix).
The PlatformEventChannelMember can't be created because it references an invalid event in the "selectedEntity" field	Use the ChangeEvent name, not the source object: AccountChangeEvent, not Account.
Cannot create a new component with the namespace: <Object>	Rename the file to use a single underscore: Account_ChangeEvent..., not Account__ChangeEvent....
The selected field, X.Y, isn't valid (in <enrichedFields>)	Replace Owner.Name with OwnerId. CDC enriches the lookup automatically; only single-hop field API names validate.
filter expression has syntax errors: unexpected token: 'WHERE'	Remove the WHERE keyword. The body is the predicate only.
The BillingCity field in the filter expression is invalid (or any flat Address component)	Use the compound dotted form: BillingAddress.City, not BillingCity. See references/filter-expressions.md for the full compound-field matrix.
Custom-object member fails with "ChangeEvent doesn't exist"	The source object isn't deployed yet. Ensure the Foo__c object metadata is in the same deploy or already in the org.
DUPLICATE_VALUE on second deploy	The member is already subscribed. Either delete first or skip — CDC doesn't support upsert on members directly.
sf infra error (TypeInferenceError, DeployMetadata): Could not infer a metadata type for a .changeDataCapture-meta.xml file	That file extension and metadata type don't exist. Replace the changeDataCapture/<Entity>.changeDataCapture-meta.xml file with a platformEventChannelMembers/<Entity>_ChangeEvent.platformEventChannelMember-meta.xml file.
User says "subscribe Order__c" but means standard Order	Confirm — OrderChangeEvent (standard) and Order__ChangeEvent (custom) are different entities.

---

Output Expectations

Deliverables:

• One force-app/.../platformEventChannelMembers/<Entity>_ChangeEvent.platformEventChannelMember-meta.xml per subscribed entity.
• One force-app/.../platformEventChannels/<DevName>__chn.platformEventChannel-meta.xml per custom channel (if any).

File structure follows the templates in assets/.

After receiving the generated files, the user can verify them with sf project deploy start --dry-run -d <path> --target-org <alias> before deploying. If a dry-run surfaces an unfamiliar error, references/deploy-troubleshooting.md maps the common deploy errors to their metadata-side fixes.

---

Cross-Skill Integration

Need	Delegate to
Generate the source custom object	platform-custom-object-generate skill
Generate custom fields referenced by enrichment or filter	platform-custom-field-generate skill
Build a permission set for users who consume change events	platform-permission-set-generate skill

---

Reference File Index

File	When to read
assets/PlatformEventChannelMember-template.xml	Step 3 — starting structure for a channel member
assets/PlatformEventChannel-template.xml	Step 4 — starting structure for a custom channel
references/filter-expressions.md	Step 6 — for the supported operators and field-type matrix when writing a filter expression
references/deploy-troubleshooting.md	When a user reports a dry-run deploy error and asks for help diagnosing it