fix: relaunch.sh — prefer ~/.dotnet SDK and skip Xcode version check

[btessiau]

Problem

relaunch.sh fails on machines where:

1. .NET 10 SDK is installed via dotnet-install.sh — installs to ~/.dotnet/, but the system dotnet at /usr/local/share/dotnet/ is an older version (e.g. 7.0). The script's bare dotnet build picks the wrong one.

2. Xcode is a minor version ahead of what the .NET MacCatalyst SDK expects (e.g. Xcode 26.3 vs expected 26.2), causing the build to fail with a version mismatch error.

Fix

• PATH: Prepend ~/.dotnet to PATH if ~/.dotnet/dotnet exists. Conditional — no-op on machines with a single system-wide install.
• Xcode: Pass -p:ValidateXcodeVersion=false to dotnet build. Apple ships Xcode updates faster than .NET SDK updates, so this mismatch is common.

[btessiau]

PR #324 Review -- Multi-Model Consensus Report

CI Status: ⚠️ No checks configured
Models used: claude-opus-4.6 ×2, claude-sonnet-4.6, gemini-3-pro-preview, gpt-5.3-codex

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✅ PATH prepend is correct

The [ -x "$HOME/.dotnet/dotnet" ] guard, timing (before first dotnet invocation), and process-local export are all sound. No issues found.

🟡 MODERATE -- ValidateXcodeVersion=false is unconditional (3/5 models flagged)

PolyPilot/relaunch.sh:33 -- The flag correctly silences minor Xcode version skew (the stated intent), but also silences major version incompatibilities. Since relaunch.sh kills the old app before launching the new build, a silently broken binary is more disruptive here than a clear build error.

Mitigating factor: Actual clang/linker failures will still surface -- the risk is narrow (codegen succeeds but runtime differs).

Suggested fix: Add a comment documenting the tradeoff:

# -p:ValidateXcodeVersion=false bypasses the .NET SDK's Xcode version-string gate.
# Safe for minor version skew (Apple ships Xcode faster than .NET certifies it).
# A major Xcode incompatibility will still surface as a compile/link error.

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Recommendation: ⚠️ Request changes (minor)

Add the explanatory comment above, then this is ready to merge. The code changes themselves are correct and well-scoped.

[btessiau]

PR #324 Review -- Multi-Model Consensus Report

CI Status: ⚠️ No checks configured
Models used: claude-opus-4.6 ×2, claude-sonnet-4.6, gemini-3-pro-preview, gpt-5.3-codex

---

✅ PATH prepend is correct

The [ -x "$HOME/.dotnet/dotnet" ] guard, timing (before first dotnet invocation), and process-local export are all sound. No issues found.

🟡 MODERATE -- ValidateXcodeVersion=false was unconditional with no comment (3/5 models flagged)

PolyPilot/relaunch.sh:33 -- The flag correctly silences minor Xcode version skew (the stated intent), but also silences major version incompatibilities. Since relaunch.sh kills the old app before launching the new build, a silently broken binary is more disruptive here than a clear build error.

Status: ✅ FIXED -- A 3-line comment block has been added documenting the tradeoff. All 5 models confirmed the fix in re-review.

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Recommendation: ✅ Approve

All previous findings have been addressed. The code changes are correct and well-scoped.