[alex-clickhouse]

Stack (merge in this order): this PR (generic hosted channel behaviour) -> #601 the email channel. The channel gateway that sends the new capabilities members and the email events ships first.

---

What

• The channel contract model reads two optional members of a connection's
  capabilities: provider and behaviour (answer: post or tool,
  reply_tool, session: rotate or keep). A copy of the contract's
  new sample capabilities_behaviour.json is in
  tests/fixtures/channel_contract/.
• A table of hosted chat providers (nerve/channels/hosted/providers.py)
  replaces the fixed Slack list. Each entry gives the provider's hosted mode,
  its switch, its channel settings, and what its channel does while the
  provider is switched off. Slack is the only entry.
• A hosted channel uses only the connections of its own provider when the
  gateway names the provider.
• A hosted channel rejects an event on a connection that announces another
  provider and sends no operation through such a connection.
• The router resolves the session of one conversation one message at a
  time, so simultaneous first messages share one session.
• In tool mode, Nerve posts nothing for a turn: no typing mark, no
  streamed placeholder, no answer, and no "Error:" message. The answer stays
  in the session. Nerve puts one line before the turn's text that says where
  the message came from, that the answer goes to no one, and which tool can
  answer.
• In keep mode, a conversation continues its last session, however long
  it was idle, while that session is not archived or deleted.

How

• ConnectionBehaviour and the new Capabilities members follow the
  gateway's checks. Absent members have the defaults post, no tool, and
  rotate, so an older gateway changes nothing.
• HostedChatProvider entries give hosted, switched_on, settings
  (HostedChannelSettings, with defaults for a provider without a Slack
  section), hold_while_off, and channel_options. Slack holds its events
  while it is off, as before. Any other provider rejects its events while it
  is off (configuration_invalid), so it never stops the inbox reader.
• StreamManager.connections() and OperationRunner.connections() take an
  optional provider.
• InboundMessage.post_answer tells the router to skip all channel output
  for a turn. The hosted channel sets it from the behaviour of the event's
  connection and, for keep, sets session_id to the conversation's last
  session.

Why

A provider such as email has no conversation that Nerve can post to, its
conversations can be idle for days, and it has no Slack-shaped settings.
Before this change, Nerve could only serve Slack: a second provider stopped
the inbox reader, shared Slack's connections, and got automatic answers and
new sessions after two idle hours. Email is added on top of this in a
separate PR.

Notes

• No visible change for Slack. A switched-off hosted Slack still holds the
  events of every hosted provider, as it holds GitHub records today, and a
  hosted channel with 100 turns in progress pauses the reading for every
  provider; both are in docs/config.md.
• Deploy order: the gateway that sends the new members ships first. Older
  Nerves ignore them.

Tests

New tests/test_hosted_channel_behaviour.py (a second provider without a
config section, refuse while off, scoping with two providers, a connection
of another provider, tool mode posts nothing and a real engine stores the
answer, the note line, keep vs rotate, simultaneous first messages, router
batches) and contract tests, including the fixture's SHA-256. Existing hosted channel tests pass unchanged.

🤖 Generated with Claude Code

[nerveai]

Nerve PR review · ✅ Ready to merge

Updated for 22fb672: another rebase onto main 85bb512. The PR's content is identical (range-diff: 9 same, 1 changed only in context). Main's #415 gave send_file a keyword-only session_id, and the rebase keeps it in the hosted channel and the router (channel.py:698, router.py:486). Verdict unchanged.

This is the base that #601 (email) stacks on. It replaces the hard-coded Slack list with a provider table (hosted/providers.py), scopes each hosted channel to its own provider's connections, and reads a per-connection behaviour (answer: post|tool, session: rotate|keep). When those members are absent, Slack keeps today's behaviour. The router lock lets simultaneous first messages share one session, which helps every channel.

Completeness: a behaviour suite, including a real engine that stores a tool-mode answer; contract tests with a pinned sample; config.md and architecture.md updated; no config keys, no migration.

Worth considering (both matter once #601 adds tool mode):

• Unknown capabilities default to post/rotate (channel.py:1154), while the reader starts at negotiation (stream.py:442). A backlog read on wake can therefore get a fresh session and no reply-tool note.
• A tool-mode turn that a drain refuses is already acked and only logged (channel.py:1181).

_{Checked: full suite in an offline sandbox at 22fb672 (3 chunks): 8866 passed, 39 skipped; test_slack_integration.py excluded (hangs offline on main too); GitHub CI green; merges cleanly into main; range-diff vs a27f301; read router.py, base.py, channel.py · automated review by nerveai — mention @nerveai to ask a follow-up.}

[alex-clickhouse]

Rebased onto main d87526e (8489a28 -> a27f301, the same 10 commits). #601 is restacked on it.

Conflicts and how they were merged:

• channel.py, runtime.py: main (Settings page, with a Notifications section #625) sends every hosted card with notify and removes HostedChannel(notification_target=...). The provider table keeps that rule: _slack_channel_options gives no notification_target, and the config does not choose the card's conversation.
• base.py: InboundMessage has both conversation_title (main, Sessions: record and show what started each session #621) and post_answer.
• router.py: the per-conversation resolution lock stays, and get_active_session gets main's conversation_title.
• docs/architecture.md: the provider paragraph uses main's notification sentence.

Checked: hosted, channel and contract tests plus test_slack_channel, test_session_origin, test_drain, test_send_file: 1231 passed. Full backend suite on #601's tip (includes this branch): 8681 passed, 38 skipped (= 8719 collected), test_slack_integration.py excluded.