Python: feat(python): cross-channel hosting improvements (endpoint paths, Activity push, Telegram/Teams fixes) (#6307)

* Update hosting channel endpoint paths

Treat channel paths as concrete endpoint paths so built-in channels can be mounted at their defaults or at the app root without sample-specific subclasses. Update docs, tests, and the Foundry Telegram Invocations sample accordingly.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add push support to ActivityProtocolChannel

Implement the ChannelPush protocol so the Activity Protocol channel can
receive cross-channel fan-out (ResponseTarget.all_linked) and echo_input
replay as a non-originating destination:

- Add push() that reconstructs a proactive Bot Framework activity (bot/user
  swap) from the stored conversation reference and POSTs it to
  /v3/conversations/{id}/activities.
- Record a ChannelIdentity (service_url, conversation, bot, user, channel_id,
  locale) on ChannelRequest.identity so the host registers the channel under
  its isolation key for fan-out resolution.
- Route the streaming path through deliver_response so Activity-originated
  turns broadcast like Telegram/Discord.
- Add tests for push delivery, service_url validation, ChannelPush instance
  check, and inbound identity recording.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Don't delete Telegram webhook on shutdown by default

The TelegramChannel deleted its webhook on shutdown in webhook mode. During
a rolling redeploy the new revision registers the webhook on startup, then
the old revision's shutdown deletes it, silently breaking inbound delivery
until the next boot. setWebhook is overwriting/idempotent, so startup
re-asserts the webhook every boot and no teardown is needed.

Add a delete_webhook_on_shutdown flag (default False) so teardown is opt-in
for ephemeral deployments, and leave the webhook in place otherwise.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix Activity channel streaming on non-Teams channels (405 on updateActivity)

The Activity Protocol channel streamed replies the Teams way: POST a
placeholder, then PUT-edit it as tokens arrive. Only Teams supports the
updateActivity REST op; Web Chat, Direct Line and the Emulator return
405 Method Not Allowed on the PUT, so the user saw only the placeholder.

Gate the placeholder+edit flow on edit-capable channels (msteams). Other
channels now buffer the stream and POST a single final message, mirroring
the non-streaming path's fan-out and response-hook semantics. Also add a
defensive 405 fallback inside the Teams edit loop so an unexpected 405
can never strand the user on the placeholder.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(hosting-activity-protocol): don't parse Teams inline attachment content as a URI

Teams message activities include a text/html attachment whose inline
`content` is raw HTML (not a URL). _parse_activity fell back to
`attachment["content"]` and passed it to Content.from_uri, raising
ContentError ("URI must contain a scheme") and failing the whole turn,
so Teams users got no response.

Only treat `contentUrl` as a URI, require an absolute scheme, and skip
unparseable attachments defensively instead of failing the message.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* feat(hosting-activity-protocol): native slash-command dispatch for Teams/Activity

Add a commands= parameter to ActivityProtocolChannel that intercepts a
leading /command (after stripping the bot's own @mention) and dispatches
to ChannelCommand handlers, mirroring the Telegram channel. Unknown
commands fall through to the agent. The channel run_hook is applied to
command requests so handlers observe the same resolved isolation key as
ordinary messages, and handler errors are swallowed (200, no Bot Service
retry of non-idempotent commands).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* feat(hosting): silent attributed Telegram echoes + Teams markdown rendering

- hosting-telegram: send cross-channel input echoes with disable_notification
  (silent) and detect echo payloads so they aren't re-broadcast.
- hosting-activity-protocol: render outbound + push activities as textFormat
  'markdown' so Teams shows formatted replies (enables per-channel variants).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(hosting-activity-protocol): address PR #6307 review feedback

Consult the host delivery pipeline even for empty streamed replies so
ResponseTarget.none is honoured and non-originating fan-out is consulted
instead of always emitting an originating "(no response)" message. Applies
to both the progressive-edit (Teams) and buffered (Web Chat/Direct Line)
streaming paths.

Re-validate service_url against the allow-list in push(): the identity is
read from a persisted store and push runs out-of-band, so the captured
service_url must be re-checked before a bearer token is sent.

Adds tests for empty-stream host consultation/suppression on both streaming
paths and for push rejecting a disallowed service_url.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/AGENTS.md

@@ -21,6 +21,21 @@ When making changes to a package, check if the following need updates:
 - The package's `AGENTS.md` file (adding/removing/renaming public APIs, architecture changes, import path changes)
 - The agent skills in `.github/skills/` if conventions, commands, or workflows change
 
+At the end of every run, re-read `AGENTS.md` and the relevant skill files and
+update any guidance that the conversation revealed to be out of date,
+incomplete, or misleading (renamed files, changed commands, new conventions
+the user confirmed, etc.). **Before adding a new principle or rule, ask the
+user whether they want it captured as a durable principle** — do not invent
+team norms from a single conversation without explicit confirmation.
+
+## Terminology
+
+- **Avoid "GA" for Agent Framework code.** Reserve *GA* for hosted services
+  (e.g. "the Foundry service is GA"). For Agent Framework packages, features,
+  and APIs use **"released"** or **"stable"** depending on context — these
+  match the feature-lifecycle stages documented in the
+  `python-feature-lifecycle` skill.
+
 ## Pull Request Description Guidance
 
 When preparing a PR description: