fix: add find projection step to IR for resilient outputComponents extraction

[sushil-kamble]

Fixes #143

Problem

Project.generate() and Screen.edit() crash with:

TypeError: Cannot read properties of undefined (reading 'screens')

The root cause is that both methods hardcode outputComponents[0] to locate the design component, but the Stitch API now returns a designSystem component at index 0 and the actual design component at index 1:

outputComponents[0] → { designSystem: { ... } }       // no .design
outputComponents[1] → { design: { screens: [...] } }   // actual screen
outputComponents[2] → { text: "..." }
outputComponents[3+] → { suggestion: "..." }

SessionOutputComponent is a polymorphic union type with no ordering guarantee — hardcoding any index is fragile.

Solution

This PR takes the approach suggested in #143 (comment): instead of patching the index from 0 to 1 (as in PR #145), it adds proper find semantics to the ProjectionStep IR so the code generator emits .find((c: any) => c.design) — making extraction resilient to future API response ordering changes.

Changes

scripts/ir-schema.ts

• Adds find: z.string().optional() to ProjectionStep
• Updates refine() to forbid combining find with index or each

scripts/generate-sdk.ts

• emitProjection(): emits .find((c: any) => c.X) for find steps
• validateProjection(): treats find like index when unwrapping array item schemas

packages/sdk/generated/domain-map.json

• Changes outputComponents projection step in generate_screen_from_text and edit_screens from { "index": 0 } to { "find": "design" }

Generated files

• Regenerated via bun run generate — project.ts now emits:

  raw.outputComponents.find((c: any) => c.design).design.screens[0]

Tests

• scripts/test/ir-schema.test.ts: 3 new tests (accepts find, rejects find+index, rejects find+each)
• scripts/test/generate-sdk.test.ts: asserts correct .find(...) expression output
• packages/sdk/test/unit/sdk.test.ts: updates mocks to reflect the real API shape (designSystem at [0], design at [1]) for generate and edit

Test plan

• All 77 SDK unit tests pass (npm run test)
• All 61 script tests pass (npm run test:scripts)
• Full smoke check passes (npm run test:smoke)
• Formatted with Prettier (npx prettier --write .)
• bun run generate produces clean output with correct .find(...) expression

Why find over index: 1

PR #145 changes index: 0 → index: 1, which fixes the immediate crash but remains fragile — the next time the API adds or reorders a component, the index breaks again. The find approach queries by presence of a property, which is semantically stable regardless of array ordering.

🤖 Generated with Claude Code

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[sushil-kamble]

Removing it.