AI: Update PHP AI Client to 1.4.0 and introduce WP_AI_Client_Embedding_Builder

[JasonTheAdams]

What

Updates the bundled PHP AI Client library to 1.4.0 and introduces embedding generation support in core.

Library update

Regenerated src/wp-includes/php-ai-client/ via bash tools/php-ai-client/installer.sh --version=1.4.0. The headline feature of 1.4.0 is embedding generation: a new EmbeddingBuilder, embedding lifecycle events, Embedding/EmbeddingResult DTOs, and a shared ModelResolver. See the 1.4.0 release notes for a full list of changes.

New: WP_AI_Client_Embedding_Builder

A WordPress wrapper around the SDK's new EmbeddingBuilder, following the exact pattern established by WP_AI_Client_Prompt_Builder:

• snake_case method naming proxied to the SDK's camelCase methods via __call().
• WP_Error handling instead of exceptions: non-generating methods never throw; once an error occurs the instance enters an error state that preserves the fluent interface, and the WP_Error is returned from the generating methods (generate_embedding_result(), generate_embedding(), generate_embeddings()).
• Respects wp_supports_ai() and the existing wp_ai_client_default_request_timeout filter.
• Adds a wp_ai_client_prevent_embedding filter, analogous to wp_ai_client_prevent_prompt.
• Error codes use an embedding_* prefix (e.g. embedding_network_error, embedding_invalid_argument) with HTTP status codes for REST-friendly errors.

Also introduces the variadic wp_ai_client_embedding() entry point, analogous to wp_ai_client_prompt():

$embeddings = wp_ai_client_embedding( 'first input', 'second input' )->generate_embeddings();

Testing

• php -l and PHPCS pass on all changed files.
• Autoloader smoke test: WordPress\AiClient\AiClient resolves after the update.
• Verified via reflection that all 11 proxied snake_case methods map to existing EmbeddingBuilder methods.

🤖 Generated with Claude Code

Shared base class: WP_AI_Client_Builder

Since the prompt and embedding builders share nearly all of their machinery, it now lives in an abstract WP_AI_Client_Builder base class: the snake_case __call() proxying, WP_Error error-state handling, exception-to-WP_Error conversion, and default request timeout setup. Child classes supply the SDK builder, error code prefix, prevent filter, and method maps via abstract methods. No behavior changes for WP_AI_Client_Prompt_Builder — error codes, filter names, and _doing_it_wrong() notices (which report the concrete class name) are identical to 7.0.

Test updates

PHP AI Client 1.4.0 moved model selection state (model, registry, providerIdOrClassName, requestOptions) from the SDK PromptBuilder onto its new ModelResolver; the test reflection helper now follows properties there.

Dedicated tests were added for WP_AI_Client_Embedding_Builder and wp_ai_client_embedding(), covering the wrapper behavior (not the SDK): constructor input parsing, timeout filter handling, fluent proxying and error-state semantics, the wp_supports_ai() / wp_ai_client_prevent_embedding gates, exception-to-WP_Error mapping, and generation via a mock embedding model. The full ai-client group passes: 298 tests, 747 assertions.

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Props jason_the_adams, dkotter.

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[dkotter]

Haven't tested this out yet but overall this looks good to me, noting most of what's here is coming from the PHP AI Client repo so I haven't reviewed any of that closely. Left a few comments that may be worth discussing

[dkotter]

A lot of the things in this class are pretty close duplicate of what's in the WP_AI_Client_Prompt_Builder, if not a full duplicate (like exception_to_wp_error, is_support_check_method, is_generating_method, get_builder_callable, snake_to_camel_case).

Any thoughts around extracting any of that duplicate functionality out into some sort of shared class/trait/something to avoid duplicate code?

[JasonTheAdams]

What do you think about this? efeb6ed