Select Python 3.11+ interpreter in install-dev.sh

[ZeshiWu]

Problem

scripts/install-dev.sh used the bare python3 to create the venv. On a machine where python3 resolves to an older interpreter (e.g. 3.9), pip silently filters out dependency versions that require 3.10+ and fails:

ERROR: Could not find a version that satisfies the requirement fastapi<0.136,>=0.135
ERROR: No matching distribution found for fastapi<0.136,>=0.135

The project requires Python 3.11+, but the script gave no hint that the interpreter was the root cause.

Fix

• Probe for the first interpreter that satisfies Python 3.11+ (python3.14 → 3.13 → 3.12 → 3.11 → python3).
• Fail fast with a clear message if none is found, instead of building a broken venv.
• Upgrade pip inside the fresh venv so newer wheel metadata resolves correctly.

Validation

bash scripts/test_backend.sh   # 117 passed
npm test                       # 244 passed
npm run build                  # ok

Also dry-ran the interpreter-selection logic (picks a 3.11+ interpreter) and re-ran a full local install to confirm dependencies install cleanly.

🤖 Generated with Claude Code