feat(fetch): implement Response.ok/statusText and Body.text/bytes/arrayBuffer

[Sonic-Y3k]

Response.ok, Response.statusText, and the Body.text(), Body.bytes() and Body.arrayBuffer() consumers were unimplemented and threw "Not implemented". (Response.ok's error message invited an issue/PR.)

• Response.Ok() (status in 200–299) and Response.StatusText() added to the Go fetch.Response type.
• Body.text/bytes/arrayBuffer implemented as custom implementations.
• Driven through the code generator (config in fetch_configuration.go); the regenerated files are committed and the codegen is idempotent.

Independent of #270 — both touch internal/fetch but in separate regions/files, so they merge in any order.

Testing: TestResponseOk/TestResponseStatusText plus a scripttests "Response surface" case (ok/status/statusText/text/json/bytes/arrayBuffer + 404).

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AI disclosure: This change was developed with the help of an AI coding assistant. I've reviewed and tested it myself; it follows the existing conventions and the full test suite (main module, v8engine, sobekengine) passes locally.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 064c3509-5b4e-437b-ae81-346089510873

📥 Commits

Reviewing files that changed from the base of the PR and between d14cd8a and 5a92f33.

📒 Files selected for processing (5)

• internal/code-gen/scripting/configuration/fetch_configuration.go
• internal/fetch/response_test.go
• scripting/internal/fetch/body.go
• scripting/internal/fetch/response.go
• scripting/internal/scripttests/fetch_suite.go

Walkthrough

This PR extends the fetch API implementation by adding Response convenience methods and Body content readers. The core work introduces Response.Ok() (status range check) and Response.StatusText() (reason phrase extraction) to internal/fetch/fetch.go, along with unit tests. The code generator configuration is updated to treat these as custom implementations. The scripting layer then exposes these methods as JavaScript-callable bindings (Response_ok, Response_statusText, Body_text, Body_bytes, Body_arrayBuffer), and integration tests validate the complete behavior across success and error scenarios.

Possibly related PRs

• gost-dom/browser#176: Refactors the Response struct in internal/fetch/fetch.go's status and underlying httpResponse handling as foundational work for the response plumbing that this PR builds upon.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and specifically describes the main implementation: adding Response.ok/statusText and Body.text/bytes/arrayBuffer methods as previously unimplemented fetch API features.
Description check	✅ Passed	The description is directly related to the changeset, providing context about what was unimplemented, listing the specific features added, explaining the implementation approach via code generation, and noting testing coverage.
Docstring Coverage	✅ Passed	Docstring coverage is 85.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[coderabbitai]

Actionable comments posted: 3

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

scripting/internal/fetch/body.go (1)

11-70: 🧹 Nitpick | 🔵 Trivial | 💤 Low value

Consider extracting common Body consumer pattern.

All four Body consumer methods (Body_json, Body_text, Body_bytes, Body_arrayBuffer) repeat the same pattern:

instance, err := js.As[fetch.Body](cbCtx.Instance())
if err != nil {
    return nil, err
}
return codec.EncodePromise(cbCtx, promise.ReadAll(instance), encoder)

A helper function could eliminate this duplication and improve maintainability:

func encodeBodyPromise[T any](
    cbCtx js.CallbackContext[T],
    encoder codec.Encoder[T, []byte],
) (js.Value[T], error) {
    instance, err := js.As[fetch.Body](cbCtx.Instance())
    if err != nil {
        return nil, err
    }
    return codec.EncodePromise(cbCtx, promise.ReadAll(instance), encoder)
}

Then each Body method becomes a one-liner: return encodeBodyPromise(cbCtx, encoderFunc).

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: dd1f5527-2b0a-43be-8c21-56830306707c

📥 Commits

Reviewing files that changed from the base of the PR and between ac2cda7 and 4f09dcb.

📒 Files selected for processing (8)

• internal/code-gen/scripting/configuration/fetch_configuration.go
• internal/fetch/fetch.go
• internal/fetch/response_test.go
• scripting/internal/fetch/body.go
• scripting/internal/fetch/body_generated.go
• scripting/internal/fetch/response.go
• scripting/internal/fetch/response_generated.go
• scripting/internal/scripttests/fetch_suite.go

💤 Files with no reviewable changes (2)

• scripting/internal/fetch/response_generated.go
• scripting/internal/fetch/body_generated.go

[Sonic-Y3k]

Follow-up in d14cd8a:

• Body consumer duplication (outside-diff nitpick): extracted the shared js.As + EncodePromise pattern into an encodeBodyPromise helper. Body_json/text/bytes/arrayBuffer are now one-liners that just pass their encoder.
• Docstring coverage: added doc comments to the Response/Body script bindings, their unit/script tests, and the code-gen configureFetchSpecs config, which were the functions dragging the ratio below the 80% threshold.

No generated files changed (codegen is still idempotent), and the suite passes on both the v8engine and sobekengine engines.