feat(client): add list_all_* helpers that drain pagination

[sanjibani]

Closes #2556.

The single-page list_tools / list_resources / list_resource_templates /
list_prompts methods on ClientSession return the server's first page plus
a next_cursor; callers that don't loop on the cursor silently see only
page zero. Four new list_all_* helpers drain the cursor until the server
stops sending one and return the flattened list:

list_all_tools() -> list[Tool]
list_all_resources() -> list[Resource]
list_all_resource_templates() -> list[ResourceTemplate]
list_all_prompts() -> list[Prompt]

Each helper reuses the existing public list_* method, so per-page
post-processing keeps running across the drain (notably the 2026
x-mcp-header filter inside _absorb_tool_listing). Single-page and
empty-list cases work without looping.

Tests cover multi-page drain, single-page short-circuit, empty
result, helpers-don't-share-cursor-state, terminal-empty-page-stops
the loop, and cursor-roundtrip (server's next_cursor comes back
unchanged as params.cursor on the next request). 9 new tests in
tests/client/test_client.py; full client test suite (121 tests) passes,
ruff lint + format clean.

Addresses the design sketch in @agaonker's earlier comment on #2556
(same return type, helper naming, cursor-drain loop, malformed-cursor
safety via None-termination).

[cubic-dev-ai]

All reported issues were addressed across 2 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

19 issues found across 32 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="tests/interaction/lowlevel/test_flows.py">

<violation number="1">
P0: The keyword argument was renamed from `message_handler` to `message_callback`, but no `connect_*` function or the `Connect` protocol defines a `message_callback` parameter. This will raise a `TypeError` at runtime. Use `message_handler=collect` instead.</violation>
</file>

<file name="tests/interaction/lowlevel/test_resources.py">

<violation number="1">
P1: This call uses `message_callback=collect`, but the `Connect` protocol and every `connect_*` implementation name the parameter `message_handler`. This will raise `TypeError` at runtime — switch back to `message_handler` so the callback reaches `ClientSession`.</violation>
</file>

<file name="tests/interaction/lowlevel/test_list_changed.py">

<violation number="1">
P0: Renamed `message_handler` to `message_callback` in the `connect()` call, but the `connect` fixture's factory functions still expect `message_handler` as the keyword argument. This will raise `TypeError: ... got an unexpected keyword argument 'message_callback'` at runtime. Keep the original `message_handler=collect` invocation to match the `Connect` protocol signature.</violation>
</file>

<file name="tests/client/test_session.py">

<violation number="1">
P1: The renamed test fixtures now call `ClientSession`/`Client` with `message_callback`, but the implementation still only accepts `message_handler`. As written these tests fail before exercising the behavior under test; either the production API needs the same rename/alias, or the tests should keep using the existing `message_handler` parameter.</violation>
</file>

<file name="tests/interaction/transports/test_streamable_http.py">

<violation number="1">
P0: `connect_over_streamable_http` accepts `message_handler`, not `message_callback` — passing `message_callback=collect` will raise `TypeError` at runtime.</violation>
</file>

<file name="tests/interaction/mcpserver/test_context.py">

<violation number="1">
P0: `message_callback` is not a recognized parameter for `connect()` — this will raise `TypeError` at runtime. The protocol and all transport implementations use `message_handler`. Replace with `message_handler=collect`.</violation>
</file>

<file name="tests/server/mcpserver/test_integration.py">

<violation number="1">
P0: Passes `message_callback` to `Client(...)` but the param is named `message_handler`. This will raise `TypeError` at runtime.</violation>
</file>

<file name="tests/interaction/mcpserver/test_tools.py">

<violation number="1">
P1: `message_callback=collect` will raise `TypeError` at runtime — the `Connect` protocol and all `connect_*` factories expect `message_handler`. Switch back to `message_handler=collect`.</violation>
</file>

<file name="tests/client/test_notification_response.py">

<violation number="1">
P0: `ClientSession.__init__` expects `message_handler` (not `message_callback`) — passing `message_callback=message_callback` will raise `TypeError` at runtime and break this test.</violation>
</file>

<file name="tests/client/test_session_group.py">

<violation number="1">
P1: Assertion keyword `message_callback` doesn't match the `ClientSession.__init__` parameter name (`message_handler`). The mock will be called with `message_handler`, so this assertion will always fail. Revert to `message_handler`.</violation>
</file>

<file name="tests/interaction/lowlevel/test_progress.py">

<violation number="1">
P0: The `connect` fixture's protocol and all concrete factories accept `message_handler` as the keyword parameter, not `message_callback`. Passing `message_callback=message_callback` will raise `TypeError` at runtime because the parameter name does not match. Keep the local function name as `message_callback` if desired, but pass it as `message_handler=message_callback`.</violation>
</file>

<file name="tests/shared/test_streamable_http.py">

<violation number="1">
P0: `ClientSession.__init__` accepts `message_handler`, not `message_callback`. Passing the renamed keyword argument raises `TypeError` at session construction, causing all 8 affected tests to crash. Rename only the local function body and keep the keyword as `message_handler=message_callback`, or keep the old kwarg name.</violation>
</file>

<file name="tests/docs_src/test_elicitation.py">

<violation number="1">
P0: `Client` accepts `message_handler`, not `message_callback`. Passing `message_callback=on_message` will raise `TypeError: Client.__init__() got an unexpected keyword argument 'message_callback'`. Revert to `message_handler=on_message`.</violation>
</file>

<file name="tests/interaction/lowlevel/test_cancellation.py">

<violation number="1">
P0: `ClientSession(client_read, client_write, message_callback=message_callback)` passes a keyword argument `message_callback` that the constructor does not accept — the parameter is named `message_handler`. This will raise `TypeError` at runtime. Fix: use `message_handler=message_callback` to pass the renamed local function to the existing keyword.</violation>
</file>

<file name="tests/docs_src/test_subscriptions.py">

<violation number="1">
P0: `Client()` has no `message_callback` parameter — it's `message_handler`. This will raise `TypeError: unexpected keyword argument 'message_callback'` at construction.</violation>
</file>

<file name="tests/docs_src/test_legacy_clients.py">

<violation number="1">
P0: Passing `message_callback` to `Client()` will raise `TypeError` at init — the dataclass field is named `message_handler`, not `message_callback`. Keep `message_handler=on_message` to match the class definition.</violation>
</file>

<file name="tests/docs_src/test_context.py">

<violation number="1">
P1: `message_callback` is not a valid keyword argument for `Client`. The parameter is named `message_handler`. Passing `message_callback` would raise `TypeError` at runtime.</violation>
</file>

<file name="tests/docs_src/test_deploy.py">

<violation number="1">
P0: Using `message_callback` on `Client()` will raise `TypeError` at runtime — the dataclass only accepts `message_handler`. Change `message_callback` back to `message_handler`.</violation>
</file>

<file name="tests/interaction/_connect.py">

<violation number="1">
P1: The interaction tests that use `connect(..., message_callback=...)` will fail before they can exercise the transport, because the helper now forwards `message_callback` into `Client(...)` while the actual client API still names this parameter `message_handler`. Keeping the helper’s forwarded keyword aligned with `Client`/`ClientSession` (or renaming the production API in the same change) would avoid the unexpected-keyword error.</violation>
</file>

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>