symlx: explicit failure for TS targets with node shebang

symlx-ts-node-shebang-change.md

symlx change request: fail early for TS targets with node shebang

Problem

A TypeScript bin target can currently be direct-linked when it has a shebang, even if that shebang is node. This leads to runtime failures like:

• ERR_UNKNOWN_FILE_EXTENSION: Unknown file extension ".ts"

for targets such as src/bin/zestman.ts.

Requested change

Add explicit validation and fail early when all conditions are true:

1. target extension is TypeScript-family: .ts, .tsx, .mts, .cts
2. target has a shebang
3. shebang runtime resolves to node

Expected error guidance

Fail with a targeted message that tells the user exactly how to fix it:

• use #!/usr/bin/env tsx (or equivalent tsx shebang), or
• remove shebang and let symlx use launcher inference.

Non-goals

• do not change default hybrid behavior for other targets
• do not change collision/session/cleanup behavior
• do not reintroduce shebang mode toggles

Acceptance criteria

• TS target + node shebang fails before linking
• TS target + tsx shebang still direct-links successfully
• TS target without shebang still uses launcher inference
• JS target + node shebang remains valid direct-link
• tests cover this scenario in bin target validation and command integration