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/backend/firecracker/bottle_plan.py

@@ -18,6 +18,10 @@ class FirecrackerBottlePlan(BottlePlan):
     agent_proxy_url: str = ""
     agent_git_gate_url: str = ""
     agent_supervise_url: str = ""
+    # Per-bottle identity token the agent presents on every attributed request
+    # (egress proxy credentials, git-gate/supervise headers); set by launch
+    # from the orchestrator registration. Empty pre-registration.
+    identity_token: str = ""
 
     @property
     def container_name(self) -> str:

bot_bottle/backend/firecracker/launch.py

@@ -147,7 +147,15 @@ def launch(
             plan,
             git_gate_plan=git_gate_plan,
             egress_plan=egress_plan,
-            agent_proxy_url=f"http://{slot.host_ip}:{EGRESS_PORT}",
+            identity_token=ctx.identity_token,
+            # Deliver the identity token as egress proxy credentials — clients
+            # honor `HTTPS_PROXY=http://id:token@gw` without app changes; the
+            # gateway reads Proxy-Authorization, validates the (source_ip,
+            # token) pair, and strips it before upstream.
+            agent_proxy_url=(
+                f"http://bottle:{ctx.identity_token}"
+                f"@{slot.host_ip}:{EGRESS_PORT}"
+            ),
             agent_git_gate_url=git_gate_url,
             agent_supervise_url=supervise_url,
         )
@@ -226,7 +234,8 @@ def _agent_guest_env(plan: FirecrackerBottlePlan, host_ip: str) -> dict[str, str
     """Env injected into every agent/exec call over SSH. The VM has no
     baked process env (it just runs init), so the proxy/CA/git/supervise
     wiring is applied per-invocation."""
-    proxy_url = f"http://{host_ip}:{EGRESS_PORT}"
+    # Carries the identity token as proxy credentials (set in `launch`).
+    proxy_url = plan.agent_proxy_url or f"http://{host_ip}:{EGRESS_PORT}"
     no_proxy = f"localhost,127.0.0.1,{host_ip}"
     env: dict[str, str] = {
         "HTTPS_PROXY": proxy_url, "HTTP_PROXY": proxy_url,