Fix cmd-enter block attachment not starting a new conversation

[MaggieShan]

Description

Pressing cmd-enter while a block (or text) is selected stopped starting a new conversation with that block attached as context. The block-attach flow now works again in a single press.

Root cause

A recent change (should_start_new_conversation_for_keybinding) gates keybinding-triggered /agent / /new behind a second-press confirmation when the user is already in an active, non-empty conversation. This guards against accidental conversation resets from reflexive keypresses, but it also intercepted the deliberate "select a block → cmd-enter" flow: the first press only armed the confirmation rather than starting the conversation, so the block was never attached.

Fix

In Input::execute_slash_command, when the user has deliberately attached context (selected blocks, selected text, image/file attachments, or a document) we now skip the confirmation and start the new conversation in a single step. A new BlocklistAIContextModel::has_pending_user_context() helper centralizes that check. Auto-attached agent-view blocks are intentionally excluded since they are not a deliberate user selection. The muscle-memory protection is preserved for the empty-handed case.

Linked Issue

• The linked issue is labeled ready-to-spec or ready-to-implement.
• Where appropriate, screenshots or a short video of the implementation are included below.

Testing

Added unit tests for has_pending_user_context covering the default (empty) state and the pending-block, pending-selected-text, and pending-attachment cases. cargo check -p warp --tests and cargo clippy -p warp --lib -- -D warnings both pass.

Note: the full test binary could not be linked in the sandbox environment due to a memory limit (the linker was OOM-killed), so the new tests were validated for compilation via cargo check --tests but not executed here.

• I have manually tested my changes locally with ./script/run

Agent Mode

• Warp Agent Mode - This PR was created via Warp's AI Agent Mode

Conversation: https://staging.warp.dev/conversation/c4254450-1bca-436d-a75d-48d7b2f5094d
Run: https://oz.staging.warp.dev/runs/019eae75-a9f0-784c-923e-475937db7038

This PR was generated with Oz.