fix(php): use interface_exists instead of class_exists for GuzzleHttp\ClientInterface

[devin-ai-integration]

Description

Linear ticket: Refs https://linear.app/buildwithfern/issue/FER-10673/

class_exists('GuzzleHttp\ClientInterface') always returns false because ClientInterface is an interface, not a class. This meant the Guzzle timeout path in RetryDecoratingClient was never reached, causing users to see:

User Warning: Timeout option is not supported for the current PSR-18 client (GuzzleHttp\Client). Use Guzzle or Symfony HttpClient for timeout support.

Changes Made

• Changed class_exists → interface_exists for GuzzleHttp\ClientInterface in RetryDecoratingClient.Template.php
• Added 3 unit tests to RawClientTest.Template.php:
  • testInterfaceExistsDetectsGuzzle — confirms interface_exists detects Guzzle when installed
  • testTimeoutForwardsToGuzzleSend — verifies timeout is forwarded via Guzzle's send() with ['timeout' => 5.0]
  • testNoTimeoutDoesNotCallGuzzleSend — verifies sendRequest() is used (not send()) when timeout is null
• Regenerated all 143 seed PHP SDK fixtures
• Added unreleased changelog entry
• Updated README.md generator (if applicable) — N/A

Testing

• Unit tests added/updated
• Manual testing completed
• All 3 new tests pass locally via php vendor/bin/phpunit in seed/php-sdk/exhaustive/wire-tests (38 tests, 118 assertions)
• phpstan passes cleanly
• All 15/15 php-sdk CI shards that include my changes pass
• The 1 failing shard (api-wide-base-path-with-default) is a pre-existing phpstan error from PR chore(seed): update all seed snapshots #15999

Link to Devin session: https://app.devin.ai/sessions/d14585aa60304ee79757b9dc229aaa8d

[devin-ai-integration]

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SDK Generation Benchmark Results

Comparing PR branch against median of 5 nightly run(s) on main (latest: 2026-05-20T05:20:23Z).

Full benchmark table (click to expand)

Generator	Spec	main (generator)	main (E2E)	PR (generator)	Delta
php-sdk	square	54s (n=5)	81s (n=5)	52s	-2s (-3.7%)

main (generator): generator-only time via --skip-scripts (includes Docker image build, container startup, IR parsing, and code generation — this is the same Docker-based flow customers use via fern generate). main (E2E): full customer-observable time including build/test scripts (nightly baseline, informational). Delta is computed against generator-only baseline.
⚠️ = generation exited with a non-zero exit code (timing may not reflect a successful run).
Baseline from nightly runs on main (latest: 2026-05-20T05:20:23Z). Trigger benchmark-baseline to refresh.
Last updated: 2026-05-20 18:51 UTC