feat(react): add context derivation

[ErnestM1234]

add the ability to derive context

Greptile Summary

This PR adds context derivation support across the React/Next.js CLI extractor, the SWC Rust compiler plugin, and the Python extractor. When a translation call uses derive() in its $context attribute (e.g. <T context={derive(getFormality())}>…</T> or t("Hello", { $context: derive(getFormality()) })), the toolchain now statically resolves all possible context variants and emits one translation entry per variant, sharing a staticId to group them together.

Confidence Score: 5/5

Safe to merge; all remaining findings are P2 style/defensive improvements that do not affect the happy path.

The feature works correctly for the normal case. Both P2 findings are edge-case defensive improvements (stale metadata key and empty-array guard) that would only manifest in unusual error conditions or with dollar-prefixed $context syntax. No P0/P1 logic errors were found.

parseTProps.ts (stale $context key) and handleLiteralTranslationCall.ts / derivation/index.ts (empty contextVariants truthy check)

Important Files Changed

Filename	Overview
packages/cli/src/react/jsx/utils/jsxParsing/parseTProps.ts	Detects derive() in JSX context prop and stores as _contextDeriveExpr; else-branch also sets metadata[attrName]=code, leaving a stale $context key in metadata when derivation succeeds
packages/cli/src/react/jsx/utils/stringParsing/processTranslationCall/handleLiteralTranslationCall.ts	Adds contextVariants cross-product for string literals; truthy-check on empty array could silently swallow entries without error
packages/cli/src/react/jsx/utils/stringParsing/processTranslationCall/index.ts	Correctly resolves contextDeriveExpr → contextVariants before routing; cleans up the temporary AST expression field before structuredClone
packages/cli/src/react/jsx/utils/stringParsing/derivation/index.ts	Cross-product of content strings × context variants; same empty-array truthy-check concern when contextVariants is []
packages/cli/src/react/jsx/utils/stringParsing/derivation/containsDeriveCall.ts	Added ConditionalExpression arm so ternaries containing derive() in context are correctly detected as derive expressions
packages/next/swc-plugin/src/visitor/expr_utils.rs	Added Cond arm to contains_derive_call and has_derive_context flag to emit empty hash when $context contains derive()
packages/next/swc-plugin/src/ast/traversal.rs	Uses jsx_attr_contains_derive_call to produce empty hash when JSX context attribute contains derive(), matching TS compiler behavior
packages/python-extractor/src/extractCalls.ts	Adds extractDeriveContext to parse _context=derive() kwargs and emit cross-product entries with shared staticId on both simple and hasStaticHelpers paths
packages/compiler/src/processing/collection/processCallExpression.ts	Sets hash to empty string when hasDeriveContext is true on JSX component and translation function paths, delegating hash resolution to the CLI
packages/cli/src/react/jsx/utils/jsxParsing/parseJsx.ts	Resolves _contextDeriveExpr to contextVariants and generates cross-product JSX updates; correctly deletes _contextDeriveExpr before structuredClone to prevent AST serialization errors

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Source: context={derive(fn())} or $context=derive(fn())] --> B{CLI/Babel parse}
    B --> C[containsDeriveCall detects derive]
    C --> D[Store _contextDeriveExpr on metadata]
    D --> E[handleDerivation resolves fn return variants]
    E --> F{Resolved?}
    F -- Yes: variants=[formal,casual] --> G[contextVariants array]
    F -- No --> H[Push error, contextVariants=undefined]
    G --> I{Content type?}
    I -- JSX Tree --> J[parseJsx: emit N updates, one per context variant]
    I -- String Literal --> K[handleLiteralTranslationCall: emit N updates]
    I -- Derive content --> L[deriveExpression: cross-product content×context]
    J --> M[Each update: source + context + shared staticId]
    K --> M
    L --> M
    M --> N[Compiler: hash='' when hasDeriveContext, CLI resolves real hashes]

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Prompt To Fix All With AI

This is a comment left during a code review.
Path: packages/cli/src/react/jsx/utils/jsxParsing/parseTProps.ts
Line: 93-97

Comment:
**Stale `$context` key persists in metadata after derivation**

When `attrName` is `'$context'` (the dollar-sign sugar form) and the expression contains `derive()`, both `metadata._contextDeriveExpr = expr` and `metadata['$context'] = code` are set. `parseJsx.ts` overrides `metadata.context` with the resolved value, but `metadata['$context']` (with the dollar prefix) is never cleaned up and ends up in every emitted update payload. If the translation API treats `$context` as an alias for `context`, it would see the raw code string instead of the resolved context.

The `else` branch should be skipped when the derive expression was already captured:
```suggestion
        } else if (!(mapAttributeName(attrName) === 'context' && t.isExpression(expr) && containsDeriveCall(expr))) {
          // Only store the code if we couldn't extract a derivable value
          metadata[attrName] = code;
        }
```

How can I resolve this? If you propose a fix, please make it concise.

---

This is a comment left during a code review.
Path: packages/cli/src/react/jsx/utils/stringParsing/processTranslationCall/handleLiteralTranslationCall.ts
Line: 57

Comment:
**Empty `contextVariants` array silently drops the translation entry**

`if (contextVariants)` is truthy for `[]`. If `nodeToStrings` ever returns an empty array (e.g. a `derive()` call that resolves to zero variants), the `for` loop runs zero times and nothing is pushed to `output.updates` — the string silently disappears with no error. A length guard is safer:
```suggestion
  if (contextVariants && contextVariants.length > 0) {
```
The same pattern applies in `derivation/index.ts` where `contexts = contextVariants ?? [metadata.context]` — an empty `contextVariants` causes the entire outer content loop to produce no updates.

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (5): Last reviewed commit: "fix greptile feedback" | Re-trigger Greptile}

[ErnestM1234]

@greptileai plz re-review

[ErnestM1234]

@greptileai plz review

[ErnestM1234]

@greptileai plz review

[ErnestM1234]

@greptileai plz-review

[ErnestM1234]

@greptileai plz-review

[archie-mckenzie]

@greptile-ai please re-review