feat(gateway): mandatory identity-token attribution on every data plane (PR #354 review)

Codex review: the /31 TAP doesn't make source IP unspoofable, and the
app-layer token was returned by launch but never delivered or enforced, so
a spoofed source could select a victim bottle's policy/tokens. Make the
token mandatory and deliver it on each attributed plane (anti-spoof landed
separately as the network boundary).

Enforcement (control plane):
- `Orchestrator.resolve` now requires a matching (source_ip, identity_token)
  pair (constant-time) — no source-IP-only fallback. `/resolve` fail-closes
  (403) on a missing/empty/mismatched token.

Delivery, per plane (the token is `token_urlsafe`, safe in a URL):
- egress: proxy credentials (`HTTPS_PROXY=http://bottle:<token>@gw`). The
  addon reads `Proxy-Authorization` — from the request (HTTP) or captured at
  the CONNECT for HTTPS tunnels (keyed by client conn, cleared on disconnect)
  — validates, and strips it (+ the legacy header) before upstream.
- git-http: a URL-scoped `http.<gate>/.extraHeader: x-bot-bottle-identity`
  in the agent's git config (only over the http transport).
- supervise: `mcp add --header x-bot-bottle-identity: <token>` (claude +
  codex); the server reads the header and passes it to resolve.

Wiring: thread `ctx.identity_token` onto the firecracker + docker plans and
into the agent env/config at launch.

Verified on a KVM host: egress with the correct proxy-cred token returns
200 (HTTP and HTTPS/CONNECT), and no-token / wrong-token return 403; a real
`cli.py start --backend=firecracker` launch provisions git config + the
supervise MCP header and reaches the agent session, all under mandatory
enforcement. Fixed a `claude mcp add` arg-order bug (--header must follow
the positional name/url) found by that launch.

Transparent proxy for tools that ignore proxy env is deferred to a
follow-up (see thread); anti-spoof + host firewall remain the fail-closed
boundary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck

bot_bottle/contrib/claude/agent_provider.py

@@ -32,6 +32,8 @@ if TYPE_CHECKING:
 
 
 _SUPERVISE_MCP_NAME = "supervise"
+# App-layer identity token header (mirrors egress_addon / git_http_backend).
+_IDENTITY_HEADER = "x-bot-bottle-identity"
 
 
 def _skills_dir(guest_home: str) -> str:
@@ -301,9 +303,15 @@ class ClaudeAgentProvider(AgentProvider):
         if plan.supervise_plan is None:
             return
         info(f"registering supervise MCP server in agent claude config → {supervise_url}")
+        # Deliver the identity token as an MCP request header — the supervise
+        # daemon requires it (mandatory (source_ip, token) attribution).
+        token = getattr(plan, "identity_token", "")
+        header = (
+            f" --header {shlex.quote(f'{_IDENTITY_HEADER}: {token}')}" if token else ""
+        )
         r = bottle.exec(
             f"claude mcp add --scope user --transport http "
-            f"{_SUPERVISE_MCP_NAME} {supervise_url}",
+            f"{_SUPERVISE_MCP_NAME} {supervise_url}{header}",
             user="node",
         )
         if r.returncode != 0: