refactor: split manifest.py into domain-specific modules

Closes #157. Distributes the 1,026-line manifest.py across four
focused modules:

- _manifest_util.py: ManifestError + _as_json_object (shared base)
- manifest_git.py: GitEntry, GitUser, git-gate config helpers
- manifest_egress.py: EgressRoute, EgressConfig, PipelockRoutePolicy
- manifest_agent.py: AgentProvider, Agent

manifest.py is now the residual orchestration layer: Bottle, Manifest,
and re-exports of all public names so existing callers are unaffected.
All 867 unit tests pass.

bot_bottle/manifest_agent.py

@@ -0,0 +1,166 @@
+"""Agent configuration manifest dataclasses."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import cast
+
+from .agent_provider import PROVIDER_TEMPLATES
+from ._manifest_util import ManifestError, _as_json_object
+from .manifest_git import GitUser
+from .manifest_schema import AGENT_MODEL_KEYS
+
+
+@dataclass(frozen=True)
+class AgentProvider:
+    """Provider/template for the agent process inside a bottle.
+
+    `template` selects a built-in launch/runtime contract. `dockerfile`
+    optionally points at a custom agent-image Dockerfile while leaving
+    bot-bottle's sidecar infrastructure intact.
+
+    `auth_token` names the host env var that holds the provider's OAuth
+    token (Claude only). The provisioner injects a provider-owned egress
+    route for api.anthropic.com that re-injects this token as the Bearer
+    header, and sets a placeholder CLAUDE_CODE_OAUTH_TOKEN in the agent
+    so the Claude Code CLI starts.
+
+    `forward_host_credentials` forwards the host Codex auth token into
+    the egress sidecar (Codex only).
+    """
+
+    template: str = "claude"
+    dockerfile: str = ""
+    auth_token: str = ""
+    forward_host_credentials: bool = False
+
+    @classmethod
+    def from_dict(cls, bottle_name: str, raw: object) -> "AgentProvider":
+        d = _as_json_object(raw, f"bottle '{bottle_name}' agent_provider")
+        for k in d:
+            if k not in {"template", "dockerfile", "auth_token", "forward_host_credentials"}:
+                raise ManifestError(
+                    f"bottle '{bottle_name}' agent_provider has unknown key {k!r}; "
+                    f"allowed: template, dockerfile, auth_token, forward_host_credentials"
+                )
+        template = d.get("template", "claude")
+        if not isinstance(template, str) or not template:
+            raise ManifestError(
+                f"bottle '{bottle_name}' agent_provider.template must be a "
+                f"non-empty string"
+            )
+        if template not in PROVIDER_TEMPLATES:
+            raise ManifestError(
+                f"bottle '{bottle_name}' agent_provider.template {template!r} "
+                f"is not one of {', '.join(sorted(PROVIDER_TEMPLATES))}"
+            )
+        dockerfile = d.get("dockerfile", "")
+        if not isinstance(dockerfile, str):
+            raise ManifestError(
+                f"bottle '{bottle_name}' agent_provider.dockerfile must be a "
+                f"string (was {type(dockerfile).__name__})"
+            )
+        auth_token = d.get("auth_token", "")
+        if not isinstance(auth_token, str):
+            raise ManifestError(
+                f"bottle '{bottle_name}' agent_provider.auth_token must be a "
+                f"string (was {type(auth_token).__name__})"
+            )
+        if auth_token and template != "claude":
+            raise ManifestError(
+                f"bottle '{bottle_name}' agent_provider.auth_token is only "
+                f"supported for template 'claude'"
+            )
+        forward_host_credentials = d.get("forward_host_credentials", False)
+        if not isinstance(forward_host_credentials, bool):
+            raise ManifestError(
+                f"bottle '{bottle_name}' agent_provider.forward_host_credentials "
+                f"must be a boolean (was {type(forward_host_credentials).__name__})"
+            )
+        if forward_host_credentials and template != "codex":
+            raise ManifestError(
+                f"bottle '{bottle_name}' agent_provider.forward_host_credentials "
+                "is currently only supported for template 'codex'"
+            )
+        return cls(
+            template=template,
+            dockerfile=dockerfile,
+            auth_token=auth_token,
+            forward_host_credentials=forward_host_credentials,
+        )
+
+
+@dataclass(frozen=True)
+class Agent:
+    bottle: str
+    skills: tuple[str, ...] = ()
+    prompt: str = ""
+    # Per-agent git identity (issue #94). Overlays the referenced
+    # bottle's git-gate.user per-field at `Manifest.bottle_for`. Only
+    # `user` is allowed at the agent level; `repos` stays bottle-only
+    # because it carries credentials and host trust.
+    git_user: GitUser = GitUser()
+
+    @classmethod
+    def from_dict(cls, name: str, raw: object, bottle_names: set[str]) -> "Agent":
+        d = _as_json_object(raw, f"agent '{name}'")
+        unknown = set(d.keys()) - AGENT_MODEL_KEYS
+        if unknown:
+            allowed = ", ".join(sorted(AGENT_MODEL_KEYS))
+            raise ManifestError(
+                f"agent '{name}' has unknown key(s) {sorted(unknown)}; "
+                f"allowed keys are {allowed}."
+            )
+
+        bottle = d.get("bottle")
+        if not isinstance(bottle, str) or not bottle:
+            raise ManifestError(f"agent '{name}' must declare a 'bottle' field naming a defined bottle")
+        if bottle not in bottle_names:
+            available = ", ".join(sorted(bottle_names)) or "(none defined)"
+            raise ManifestError(
+                f"agent '{name}' references bottle '{bottle}', which is not defined. "
+                f"Available: {available}"
+            )
+
+        skills: tuple[str, ...] = ()
+        skills_raw = d.get("skills")
+        if skills_raw is not None:
+            if not isinstance(skills_raw, list):
+                raise ManifestError(f"agent '{name}' skills must be an array (was {type(skills_raw).__name__})")
+            collected: list[str] = []
+            skills_list = cast(list[object], skills_raw)
+            for i, skill in enumerate(skills_list):
+                if not isinstance(skill, str):
+                    raise ManifestError(
+                        f"agent '{name}' skills[{i}] must be a string "
+                        f"(was {type(skill).__name__})"
+                    )
+                collected.append(skill)
+            skills = tuple(collected)
+
+        prompt_raw = d.get("prompt")
+        if prompt_raw is None:
+            prompt = ""
+        elif isinstance(prompt_raw, str):
+            prompt = prompt_raw
+        else:
+            raise ManifestError(f"agent '{name}' prompt must be a string (was {type(prompt_raw).__name__})")
+
+        # git-gate: agents may declare only `git-gate.user` (name/email).
+        # `git-gate.repos` is bottle-only — it carries credentials and host trust.
+        git_user = GitUser()
+        git_raw = d.get("git-gate")
+        if git_raw is not None:
+            gd = _as_json_object(git_raw, f"agent '{name}' git-gate")
+            for k in gd.keys():
+                if k != "user":
+                    raise ManifestError(
+                        f"agent '{name}' git-gate.{k} is not allowed at the "
+                        f"agent level; only git-gate.user (name/email) may be "
+                        f"set on an agent. git-gate.repos is bottle-only "
+                        f"(it carries credentials and host trust)."
+                    )
+            if "user" in gd:
+                git_user = GitUser.from_dict(name, gd["user"])
+
+        return cls(bottle=bottle, skills=skills, prompt=prompt, git_user=git_user)