fix(dev): honor OMB_PORT in the vite proxy, allow OMB_UI_PORT

[jpun]

The problem

The harness server reads OMB_PORT || OGB_PORT || 8799 (server/index.ts:80), but the dev proxy only read the legacy OGB_PORT (vite.config.ts:42).

So setting OMB_PORT — the documented, non-legacy name — moves the server but not the proxy. pnpm dev silently keeps talking to 8799 and every /api call 404s, with nothing pointing at the cause.

Why it matters

Running a second instance beside the first is already almost supported:

• OMB_DATA_DIR isolates the fleet (server/config.ts:66)
• Electron probes 8799 / 18799 / 28799 (electron/main.mjs:173)

The dev UI was the one piece that couldn't follow. The vite dev port was hardcoded as well, so two pnpm dev processes collide on 5199.

The change

• proxy target reads OMB_PORT first, keeping OGB_PORT as fallback
• dev server port reads OMB_UI_PORT, defaulting to 5199

Two lines. Fully backward compatible — with both variables unset the behavior is byte-identical to before.

Verification

pnpm typecheck   # passes
npx oxlint vite.config.ts   # clean

Two instances side by side:

# instance A — unchanged defaults
pnpm dev:server && pnpm dev

# instance B
OMB_DATA_DIR="$HOME/.openmausbot-dev" OMB_PORT=18799 pnpm dev:server
OMB_PORT=18799 OMB_UI_PORT=15199 pnpm dev

Happy to drop the OMB_UI_PORT half if you'd rather keep the dev port fixed — the proxy fix is the part that's actually a bug.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Configuration
  • The development server port can now be customized through OMB_UI_PORT, with port 5199 used by default.
  • API proxy routing now supports configurable backend ports, with fallback options for improved setup flexibility.

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ℹ️ Recent review info

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• vite.config.ts

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📝 Walkthrough

Walkthrough

Vite now reads OMB_UI_PORT for the development server and uses OMB_PORT, OGB_PORT, or 8799 for the /api proxy target.

Changes

Vite port configuration

Layer / File(s)	Summary
Environment-based port selection vite.config.ts	The development server reads OMB_UI_PORT with a 5199 fallback. The /api proxy target prioritizes OMB_PORT, then OGB_PORT, and finally 8799.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to b8d9a

This change aligns the development proxy and UI port settings with the documented environment variables; no actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: milind-soni, mnthr7

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the proxy port fix and configurable Vite UI port.
Description check	✅ Passed	The description explains the problem, changes, rationale, verification, and compatibility impact, but omits the template checklist.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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