feat(prd-0081): reprovision CA, git-gate, and egress tokens on gateway bring-up

On a Firecracker gateway cold boot, reconcile every live agent VM against
the fresh gateway: push the new mitmproxy CA into each agent's trust store,
re-provision git-gate repos/creds from the persisted upstreams snapshot,
and restore egress tokens. Per-bottle failures are logged and skipped so
one unreachable VM does not block the rest.

New modules / changes:
- backend/firecracker/reconcile.py: attach_bottled_agents_to_gateway,
  _push_ca, _reprovision_git_gate, _guest_ip_from_config
- git_gate/provision.py: write upstreams.json after key provisioning so
  the bring-up reconcile can reconstruct the upstream table without the
  manifest
- backend/firecracker/infra.py: call attach_bottled_agents_to_gateway in
  the cold-boot branch of ensure_running()
- backend/base.py: no-op default on BottleBackend
- backend/firecracker/consolidated_launch.py: remove superseded
  _reprovision_running_bottles / _guest_ip_from_config
- orchestrator: OrchestratorCore.update_agent_secret + POST
  /bottles/<id>/secret + client.update_agent_secret (single-secret
  in-place update, the reusable primitive from the 2026-07-26 hotfix)
- tests: 15 new tests in test_firecracker_reconcile.py; updated
  test_firecracker_infra.py cold-boot cases; stale FC reprovision tests
  removed from test_backend_secret_reprovision.py

Closes #516.

bot_bottle/orchestrator/api.py

@@ -50,6 +50,12 @@ class ReprovisionBody(_StrictModel):
     env_var_secret: StrictStr
 
 
+class SecretBody(_StrictModel):
+    name: StrictStr
+    value: StrictStr
+    env_var_secret: StrictStr
+
+
 class ReconcileBody(_StrictModel):
     live_source_ips: list[StrictStr]
     grace_seconds: float | None = None
@@ -259,6 +265,21 @@ def create_app(orch: OrchestratorCore, *, signing_key: str) -> FastAPI:
             return {"reprovisioned": True}
         raise HTTPException(404, "no stored secrets for this bottle")
 
+    @app.post("/bottles/{bottle_id}/secret")
+    def update_secret(bottle_id: str, body: SecretBody) -> dict[str, object]:
+        # Update ONE egress token for a running bottle in place — the
+        # single-secret form of reprovision, for refreshing a short-lived host
+        # credential (e.g. the Codex access token) without a relaunch. cli-only
+        # (not in _GATEWAY_ROUTES): a bottle must never set its own tokens.
+        if orch.update_agent_secret(
+            bottle_id,
+            _required(body.name, "name"),
+            _required(body.value, "value"),
+            _required(body.env_var_secret, "env_var_secret"),
+        ):
+            return {"updated": True}
+        raise HTTPException(404, "no such bottle")
+
     @app.delete("/bottles/{bottle_id}")
     def teardown(bottle_id: str) -> dict[str, object]:
         if orch.teardown_bottle(bottle_id):

bot_bottle/orchestrator/client.py

@@ -184,6 +184,27 @@ class OrchestratorClient:
             )
         return True
 
+    def update_agent_secret(
+        self, bottle_id: str, name: str, value: str, env_var_secret: str,
+    ) -> bool:
+        """Update ONE egress token for a running bottle in place
+        (`POST /bottles/<id>/secret`) — the single-secret form of
+        `reprovision_gateway`, for pushing a freshly-refreshed host credential
+        into a bottle without a relaunch. Returns True on success, False when the
+        orchestrator doesn't know the bottle (404)."""
+        status, _ = self._request(
+            "POST",
+            f"/bottles/{bottle_id}/secret",
+            {"name": name, "value": value, "env_var_secret": env_var_secret},
+        )
+        if status == 404:
+            return False
+        if not 200 <= status < 300:
+            raise OrchestratorClientError(
+                f"update_agent_secret {bottle_id}: HTTP {status}"
+            )
+        return True
+
     def teardown_bottle(self, bottle_id: str) -> bool:
         """Tear a bottle down (`DELETE /bottles/<id>`). False if the
         orchestrator didn't know it (404) — idempotent for cleanup paths."""

bot_bottle/orchestrator/lifecycle.py

@@ -63,12 +63,10 @@ class Orchestrator(abc.ABC):
     # orchestrator never starts without its signing key.
     provisioning: ControlPlaneProvisioning = ControlPlaneProvisioning()
 
-    def ensure_available(self) -> None:
-        """Acquire the exact image/rootfs selected for this application."""
-        self.ensure_built()
-
     def ensure_built(self) -> None:
-        """Local-build implementation hook retained for backend compatibility."""
+        """Ensure the orchestrator's image / rootfs exists, building it if
+        needed. Default: nothing to build (e.g. a pre-pulled image). Call before
+        `ensure_running`."""
         return
 
     @abc.abstractmethod

bot_bottle/orchestrator/service.py

@@ -379,6 +379,30 @@ class OrchestratorCore:
         self._tokens[bottle_id] = decrypted
         return True
 
+    def update_agent_secret(
+        self, bottle_id: str, name: str, value: str, env_var_secret: str,
+    ) -> bool:
+        """Update ONE egress token for a known bottle in place — the
+        single-secret form of ``reprovision_from_secret``.
+
+        Sets the in-memory token AND upserts the single re-encrypted row under
+        *env_var_secret* (the same key the rest of the rows are encrypted with, so
+        the whole set stays decryptable by a later ``reprovision_from_secret``),
+        leaving every other token untouched. Returns False if the bottle is
+        unknown.
+
+        Unlike ``reprovision_from_secret`` (which restores the values captured at
+        launch), this pushes a *caller-supplied* value — used to refresh a
+        short-lived host credential (e.g. the Codex access token) into a
+        still-running bottle without a relaunch."""
+        from .store.secret_store import encrypt_value
+        if self.registry.get(bottle_id) is None:
+            return False
+        self._tokens.setdefault(bottle_id, {})[name] = value
+        self.registry.store_agent_secret(
+            bottle_id, name, encrypt_value(env_var_secret, value))
+        return True
+
     # --- consolidated gateway ----------------------------------------------
 
     def gateway_status(self) -> dict[str, object]:

bot_bottle/orchestrator/store/registry_store.py

@@ -370,6 +370,30 @@ class RegistryStore(DbStore):
             )
         self._chmod()
 
+    def store_agent_secret(
+        self,
+        bottle_id: str,
+        key: str,
+        encrypted_value: str,
+        secret_type: str = "injected_env_var",
+    ) -> None:
+        """Upsert ONE encrypted secret row (env-var name → ciphertext) for
+        *bottle_id*, leaving the bottle's other secrets untouched — the per-key
+        counterpart of ``store_agent_secrets``' replace-all. Delete-then-insert
+        because the table carries no unique constraint to `ON CONFLICT` against."""
+        with self._connection() as conn:
+            conn.execute(
+                "DELETE FROM bottled_agent_secrets "
+                "WHERE bottled_agent_id = ? AND key = ? AND type = ?",
+                (bottle_id, key, secret_type),
+            )
+            conn.execute(
+                "INSERT INTO bottled_agent_secrets "
+                "(bottled_agent_id, key, value, type) VALUES (?, ?, ?, ?)",
+                (bottle_id, key, encrypted_value, secret_type),
+            )
+        self._chmod()
+
     def get_agent_secrets(
         self,
         bottle_id: str,