feat(orchestrator+egress): slice 8 — multi-tenant egress via the resolver (#352)

The egress addon now selects each request's Config by the calling bottle's
source IP, so one shared sidecar serves every bottle. Opt-in and fail-closed;
single-tenant behaviour is unchanged.

Orchestrator side (source-IP-primary attribution, per the PRD invariant):
  * registry: `by_source_ip` (the single active bottle at a source IP —
    network-layer attribution); `attribute` now composes it + the token.
  * service: `resolve(source_ip, token="")` — with a token, strict
    attribution; without, source IP alone.
  * control_plane: `POST /resolve`'s identity_token is now OPTIONAL (absent
    → source-IP-only); split cleanly from the token-required `/attribute`.
  * policy_resolver: `resolve` token now optional.

Egress side:
  * egress_addon_core: `resolve_client_config(resolver, client_ip, token)` —
    fetches + parses the client's Config, **fail-closed**: unattributed, a
    resolver error, or an unparseable policy all yield deny-all (no routes).
    Host-testable; `PolicyResolverLike` Protocol keeps it import-free.
  * egress_addon: consolidated mode when `BOT_BOTTLE_ORCHESTRATOR_URL` is
    set → `_active_config(flow)` resolves per client IP (reads + strips the
    `x-bot-bottle-identity` header); `request()` uses it. Unset → the static
    routes file, exactly as before. `PolicyResolver` added to the bundle.

Security note: source-IP-only resolution is safe where the IP is unspoofable
(Firecracker /31 + nft) AND the control plane is reachable only by the
trusted sidecar; the identity token, when the agent injects it, strengthens
it on weaker backends.

Scope note: the egress data plane is now multi-tenant. Remaining to be fully
live: the network topology routing every bottle's proxy to the one shared
sidecar, git-gate multitenancy, and agent-side identity-token injection.

Tests: registry by_source_ip; orchestrator resolve (with/without token);
control-plane /resolve token-optional; resolver token-optional;
resolve_client_config fail-closed matrix. All 182 egress tests still pass
(single-tenant unchanged). Full suite green.

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

bot_bottle/egress_addon_core.py

@@ -413,6 +413,34 @@ def load_config(text: str) -> "Config":
     return parse_config(payload)
 
 
+class PolicyResolverLike(typing.Protocol):
+    """The bit of `policy_resolver.PolicyResolver` this module needs — kept a
+    Protocol so egress_addon_core stays free of that import."""
+
+    def resolve(self, source_ip: str, identity_token: str = ...) -> "str | None":
+        ...
+
+
+def resolve_client_config(
+    resolver: PolicyResolverLike, client_ip: str, identity_token: str = ""
+) -> "Config":
+    """The calling client's egress Config, resolved from the orchestrator via
+    `resolver` and parsed — **fail-closed**. An unattributed client (None), a
+    resolver error, or an unparseable policy all yield a deny-all Config (no
+    routes → every request blocked). A compromised, absent, or confused
+    orchestrator must never *widen* a bottle's egress."""
+    try:
+        policy = resolver.resolve(client_ip, identity_token)
+    except Exception:  # noqa: BLE001  # pylint: disable=broad-exception-caught
+        return Config(routes=())  # orchestrator unreachable/errored → deny
+    if not policy:
+        return Config(routes=())  # unattributed or empty → deny-all
+    try:
+        return load_config(policy)
+    except ValueError:
+        return Config(routes=())  # unparseable policy → deny
+
+
 # ---------------------------------------------------------------------------
 # Match evaluation
 # ---------------------------------------------------------------------------
@@ -804,6 +832,8 @@ __all__ = [
     "is_git_push_request",
     "is_git_fetch_request",
     "load_config",
+    "resolve_client_config",
+    "PolicyResolverLike",
     "match_route",
     "outbound_scan_headers",
     "parse_config",