feat(mcp): resolve and negotiate the dual-era protocol selection

[ignaciojimenezr]

Stacked on #4085 — merge that first. Replaces #3828, which mixed data and behavior; this is the behavior half.

• Makes the app actually act on the auto protocol setting that feat(host-catalog): ChatGPT dual-era protocol — client data and negotiation #4085 publishes.
• On connect, auto means "don't pin a version" — the client negotiates the era with the server instead of announcing one up front.
• The host's protocol dropdown gains the matching Automatic option.
• No catalog or host data changes here.

🤖 Generated with Claude Code

---

Summary by cubic

Implements automatic MCP protocol negotiation across the 2025/2026 eras and treats "auto" as a stored selection policy. Automatic now negotiates the era on connect (no wire pin) and respects the client’s advertised support list, which can change reconnect behavior.

• Host defaults may now be "auto". At connect time the SDK reduces "auto" to no pin and negotiates via discovery; explicit server pins still win. The connection profile never emits "auto" on the wire.
• The manager honors supportedProtocolVersions in Automatic mode (per-server or manager default). It negotiates only within that list and rejects servers that counter-offer an unlisted version. Explicit pins remain strict.
• The protocol dropdown adds an Automatic option. Selecting it persists "auto"; legacy rows with no pin render as Automatic without rewriting. The dropdown only offers advertised versions and warns on any unadvertised pin.

Review and rollout

• Config shape: mcpProfile.mcpProtocolVersion can be "auto" in stored configs and Host JSON; connection profiles still carry undefined for the wire pin.
• If you set supportedProtocolVersions (per server or manager default), include all eras you want to negotiate; Automatic will fail when the server selects a version outside that list. No data migration is required.

^{Written for commit 008b419. Summary will update on new commits.}

[chatgpt-codex-connector]

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.
Credits must be used to enable repository wide code reviews.

[chelojimenez]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.

[github-actions]

Internal preview

Preview URL: https://mcp-inspector-pr-4086.up.railway.app
Deployed commit: eb8c7bb
PR head commit: 008b419
Backend target: staging fallback.
Health: ✅ Convex reachable
Access is employee-only in non-production environments.