fix: handle default values for slicingArguments

[ysmolski]

This PR adds support of fields defaults specified in the schema for the field arguments/paths specified in slicingArgument. That includes nested InputObjects.

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• v2/pkg/engine/plan/cost.go

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• v2/pkg/engine/plan/cost.go

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📝 Walkthrough

Walkthrough

This PR derives Int defaults for configured slicing-argument paths from the upstream SDL, exposes them on FieldListSize.SlicingArgumentDefaults, uses them when resolving slicing args for list-size multiplier calculation and RequireOneSlicingArgument validation, adds unit tests for default extraction, and wires default backfilling into data source configuration and execution tests.

Changes

Slicing argument defaults support

Layer / File(s)	Summary
Core slicing argument resolution with defaults v2/pkg/engine/plan/cost.go	FieldListSize gains SlicingArgumentDefaults map. New resolveSlicingArg helper reads slicing arguments from request variables/arguments and falls back to configured defaults when arguments are omitted. Both cost multiplier calculation and validateSliceArguments use the new resolver to treat defaulted arguments as provided.
SDL default extraction and validation v2/pkg/engine/plan/cost_defaults.go	fillListSizeDefaults populates SlicingArgumentDefaults by resolving each configured slicing-argument dot-path to an effective leaf Int default from the schema. getEffectiveSlicingArgLeafDefault traverses field arguments and nested input-object definitions, applies shadowing semantics (outer non-Int defaults override inner ones), and returns the resolved Int leaf. findObjectFieldValue inspects object-literal AST defaults.
Wiring defaults into data source configuration v2/pkg/engine/plan/datasource_configuration.go	NewDataSourceConfigurationWithName backfills SlicingArgumentDefaults for configured list sizes by fetching the upstream SDL and invoking fillListSizeDefaults when cost config and schema are available.
Unit tests for default extraction v2/pkg/engine/plan/cost_defaults_test.go	Comprehensive test suite for fillListSizeDefaults covering flat and dotted-path slicing arguments, Int default enrichment from schema, shadowing behavior (explicit null suppresses inner defaults, non-Int defaults block resolution), and graceful handling of unresolvable paths, missing schema fields, nil schema/map entries, and empty slicing-argument lists.
Integration tests: cost estimation and validation with schema defaults execution/engine/execution_engine_cost_test.go	Updated test schema naming (Search/Page replace SInput/PInput). Added tests verifying cost estimation falls back to flat defaults and nested object/dot-path defaults when operation inputs omit slicing arguments, and tests verifying RequireOneSlicingArgument treats defaulted slicing arguments as provided while treating explicit null and variable-null as absent.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• wundergraph/graphql-go-tools#1485: Both PRs modify the list-size slicing-argument resolution and validation logic in v2/pkg/engine/plan/cost.go; this PR extends resolution to consider SDL-declared defaults.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix: handle default values for slicingArguments' directly and clearly describes the main change: adding support for schema-defined default values in slicing arguments.
Description check	✅ Passed	The description accurately describes the changeset, explaining that the PR adds support for field defaults in slicingArgument configurations, including nested InputObjects.
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: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@v2/pkg/engine/plan/cost.go`:
- Around line 116-123: The current logic around resolveSlicingArgIntValue treats
any non-success as "missing" and therefore applies SlicingArgumentDefaults even
when the user explicitly provided a null or non-int value; change
resolveSlicingArgIntValue (and its call sites in the dot-path branch inside the
slicing resolution code) to return a tri-state result (e.g., found | missing |
explicit_invalid) instead of a boolean, then update the dot-path handling (the
if strings.Contains(slicingArg, ".") block) so that defaultValue is applied only
when the result is missing, not when explicit_invalid; update any downstream
checks that rely on presence (e.g., RequireOneSlicingArgument logic) to treat
explicit_invalid as provided-but-unusable rather than omitted so defaults and
multiplier calculations only use SlicingArgumentDefaults for truly missing
paths.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📥 Commits

Reviewing files that changed from the base of the PR and between b08f86e and d11a77d.

📒 Files selected for processing (5)

• execution/engine/execution_engine_cost_test.go
• v2/pkg/engine/plan/cost.go
• v2/pkg/engine/plan/cost_defaults.go
• v2/pkg/engine/plan/cost_defaults_test.go
• v2/pkg/engine/plan/datasource_configuration.go

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@v2/pkg/engine/plan/cost.go`:
- Around line 129-142: The current branch in cost.go that handles flat slicing
args (the block around args[slicingArg] and the hasVariable check) returns false
when the variable is present but set to nil, preventing falling back to
SlicingArgumentDefaults; update the logic in that branch so that if
arg.hasVariable is true and vars != nil but vars.Get(arg.varName) is nil (or not
a number), it should fall through to use the defaultValue when hasDefault is
true (instead of immediately returning 0,false). Concretely: in the args lookup
path for slicingArg in the function containing this snippet, only return
vars.GetInt(...) when the variable exists and is a number; otherwise, if
hasDefault is true return defaultValue,true; keep the final return 0,false
otherwise. Also add a regression test for the case items(first: $limit) with
empty variables and an SDL default to ensure SlicingArgumentDefaults and
RequireOneSlicingArgument behave correctly.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📥 Commits

Reviewing files that changed from the base of the PR and between d11a77d and 7f161e0.

📒 Files selected for processing (3)

• execution/engine/execution_engine_cost_test.go
• v2/pkg/engine/plan/cost.go
• v2/pkg/engine/plan/cost_defaults_test.go

🚧 Files skipped from review as they are similar to previous changes (1)

• v2/pkg/engine/plan/cost_defaults_test.go

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@v2/pkg/engine/plan/cost.go`:
- Around line 137-146: The current branch inside the argument resolution block
treats a nil vars pointer as "no default" and falls through; update the logic in
the function handling slicing args so that when arg.hasVariable is true and vars
== nil it is treated as the variable being omitted (so if hasDefault is true
return defaultValue, true). Concretely, in the block that references
arg.hasVariable, vars, arg.varName, hasDefault and defaultValue, restructure the
checks to first test if vars == nil and return the default if available,
otherwise keep the existing path that calls vars.Get(arg.varName) and
vars.GetInt(arg.varName); this ensures behavior for omitted variables matches
SlicingArgumentDefaults and RequireOneSlicingArgument.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📒 Files selected for processing (2)

• execution/engine/execution_engine_cost_test.go
• v2/pkg/engine/plan/cost.go