feat(ir): carry path parameter clientDefault into dynamic IR NamedParameter

[devin-ai-integration]

Description

Additive dynamic-IR change so dynamic-snippet generators can distinguish an optional (client-default) path parameter from a required one.

This is step 1 of 2 toward fixing the php-sdk api-wide-base-path-with-default seed allowedFailures entry. Today an api-wide base-path parameter with x-fern-default (e.g. apiVersion: v1beta) carries a clientDefault in the full IR, which makes the generated SDK treat it as optional and order it after the request body:

create(Widget $request, string $apiVersion = 'v1beta', ?array $options = null)

But the dynamic snippet emits it as a required positional arg before the body (create('v1beta', new Widget([...]))), producing a phpstan type mismatch. The root cause is that the dynamic IR's NamedParameter carried variable but dropped clientDefault, so the snippet generator had no signal that the param is optional/reorderable.

The generator-side reordering fix is a separate follow-up PR that can only land after this IR change publishes (@fern-fern/ir-sdk / @fern-api/dynamic-ir-sdk), since generators consume the published IR SDK — they cannot read a field that doesn't yet exist in the published type. This PR therefore does not touch seed/php-sdk/seed.yml or remove the allowedFailures entry.

Changes Made

• Add optional clientDefault: optional<LiteralType> to the dynamic IR's NamedParameter in packages/ir-sdk/fern/apis/ir-types-latest/definition/dynamic/types.yml; regenerate the IR SDK (pnpm ir:generate).
• Populate it in DynamicSnippetsConverter.convertPathParameters (reusing the existing convertLiteral helper):

  clientDefault: pathParameter.clientDefault != null
      ? this.convertLiteral(pathParameter.clientDefault)
      : undefined

  This converter is called with this.ir.pathParameters (api-wide root params), so the base-path apiVersion param now carries its clientDefault into the dynamic IR. The IR SDK is generated with noOptionalProperties, so all other NamedParameter construction sites in the converter were updated to set clientDefault: undefined.
• Bump packages/ir-sdk/fern/apis/ir-types-latest/VERSION to 67.7.0 (minor for an additive optional field) and add an IR CHANGELOG.md entry. 67.6.0 shipped independently on main for specVersion, so this change resolves the merge by taking the next minor.
• Add a CLI changelog entry under packages/cli/cli/changes/unreleased/.
• Regenerate the @fern-api/ir-generator-tests dynamic-IR / full-IR snapshot fixtures (additive clientDefault only) and update the file-dependencies IR-length ete snapshot (2297979 → 2298004) to account for both specVersion (from main) and clientDefault.
• Updated README.md generator (if applicable) — n/a

Testing

• pnpm compile (160/160 packages) and pnpm run check (biome) pass with the new field.
• @fern-api/ir-generator-tests suite passes. The regenerated dynamic-IR snapshot for the target fixture now carries the field on the base-path param:

       "propertyAccess": null,
  -    "variable": null
  +    "variable": null,
  +    "clientDefault": {
  +        "type": "string",
  +        "value": "v1beta"
  +    }

  All other params correctly serialize "clientDefault": null.
• Full CI green (206 passed) on the merge-resolved branch, including test-ete and all seed suites.
• Unit tests added/updated — n/a (additive, covered by regenerated snapshots)

Follow-up (after this publishes): bump the php dynamic-snippets generator's IR deps, order root path params by clientDefault != null to match the SDK signature, regenerate the fixture, and remove api-wide-base-path-with-default from seed/php-sdk/seed.yml.

Link to Devin session: https://app.devin.ai/sessions/f75b71a1feab408dbe95a9e698500465

[devin-ai-integration]

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[github-actions]

Docs Generation Benchmark Results

Comparing PR branch against median of 5 nightly run(s) on main (latest: 2026-06-25T05:19:47Z).

Fixture	main	PR	Delta
docs	220.4s (n=5)	237.2s (35 versions)	+16.8s (+7.6%)

Docs generation runs fern generate --docs --preview end-to-end against the benchmark fixture with 35 API versions (each version: markdown processing + OpenAPI-to-IR + FDR upload).
Delta is computed against the nightly baseline on main.
Baseline from nightly run(s) on main (latest: 2026-06-25T05:19:47Z). Trigger benchmark-baseline to refresh.
Last updated: 2026-06-25 09:05 UTC

[github-actions]

SDK Generation Benchmark Results

Comparing PR branch against median of 5 nightly run(s) on main (latest: 2026-06-25T05:19:47Z).

Full benchmark table (click to expand)

Generator	Spec	main (generator)	main (E2E)	PR (generator)	Delta
csharp-sdk	square	71s (n=5)	109s (n=5)	62s	-9s (-12.7%)
go-sdk	square	134s (n=5)	284s (n=5)	130s	-4s (-3.0%)
java-sdk	square	213s (n=5)	282s (n=5)	191s	-22s (-10.3%)
php-sdk	square	59s (n=5)	84s (n=5)	53s	-6s (-10.2%)
python-sdk	square	136s (n=5)	241s (n=5)	127s	-9s (-6.6%)
ruby-sdk-v2	square	91s (n=5)	129s (n=5)	85s	-6s (-6.6%)
rust-sdk	square	183s (n=5)	173s (n=5)	155s	-28s (-15.3%)
swift-sdk	square	57s (n=5)	431s (n=5)	49s	-8s (-14.0%)
ts-sdk	square	236s (n=5)	239s (n=5)	235s	-1s (-0.4%)

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: 2026-06-25T05:19:47Z). Trigger benchmark-baseline to refresh.
Last updated: 2026-06-25 09:08 UTC