The session id was written to the session file right after session/new,
but the system prompt rides on the first prompt only. If that prompt
failed, the next turn (or the next harness start) resumed the recorded
session as not-new and the system prompt never reached it.
The id is now written after the first session/prompt gets its reply.
A failed first prompt leaves nothing recorded, so the next turn starts
a new session and sends the system prompt again. Chosen over a separate
"system prompt delivered" marker: one file, and "recorded" already means
"usable".
Tests drive AcpRuntime against a scripted sh agent that fails the first
prompt: in-process and across a restart, the retry is a new session
carrying the system prompt.
Also: PermissionPolicy now sees a PermissionAsk (kind plus the MCP
server the tool belongs to, matched by name against the servers handed
to the session), so a caller can tell MCP tool calls from other `other`
requests.
Refs #4391
A `Runtime` trait (run / compact / archive) with two backends:
- claude: a pass-through to hive_claude's InfiniteSession and
SessionStore, so a claude turn is the same spawn, session handling
and errors as before.
- acp: a generic Agent Client Protocol client. It spawns the command,
args and env from RuntimeSpec (HIVE_RUNTIME / HIVE_ACP_COMMAND /
HIVE_ACP_ARGS / HIVE_ACP_ENV), refuses an agent whose
mcpCapabilities.http is not true, passes the claude --mcp-config
servers as ACP mcpServers, keeps one session id in a file
(session/load after a restart, session/new otherwise), and maps
session/update into claude stream-json events plus usage_update into
Telemetry. Permission requests are answered by a caller-supplied
policy on the ACP tool kind. compact returns Unsupported for now.
The crate depends on no hyperhive binary crate, so the subagent
daemon can move onto it without pulling in hive-agent.
Refs #4391
