feat(linear): Auto link Linear issues from private notes (#14405)

When an agent pastes a Linear issue URL into a private note on a
conversation, Chatwoot now links the issue to the conversation
automatically — no need to click "Link to Linear issue" first. The
standard activity message ("X linked Linear issue ABC-123") is posted
just like a manual link.

Fixes
[CW-7032](https://linear.app/chatwoot/issue/CW-7032/if-someone-post-a-linear-url-in-the-private-notes-automatically-link)

---------

Co-authored-by: Muhsin <12408980+muhsin-k@users.noreply.github.com>
Co-authored-by: Sojan Jose <sojan@pepalo.com>

spec/lib/integrations/linear/auto_link_service_spec.rb

@@ -0,0 +1,178 @@
+require 'rails_helper'
+
+describe Integrations::Linear::AutoLinkService do
+  let(:account) { create(:account) }
+  let(:user) { create(:user, account: account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:conversation) { create(:conversation, account: account, inbox: inbox) }
+  let(:processor) { instance_double(Integrations::Linear::ProcessorService) }
+  let(:activity_service) { instance_double(Linear::ActivityMessageService, perform: true) }
+
+  let(:linear_url) { 'https://linear.app/chatwoot/issue/CW-1234/some-slug' }
+  let(:identifier) { 'CW-1234' }
+  let(:node_id) { 'linear-node-id-1' }
+  let(:search_response) do
+    { data: [{ 'id' => node_id, 'identifier' => identifier, 'title' => 'Issue title',
+               'url' => 'https://linear.app/chatwoot/issue/CW-1234/issue-title' }] }
+  end
+
+  before do
+    allow(Integrations::Linear::ProcessorService).to receive(:new).with(account: account).and_return(processor)
+    allow(Linear::ActivityMessageService).to receive(:new).and_return(activity_service)
+    allow(processor).to receive(:linked_issues).and_return({ data: [] })
+    allow(processor).to receive(:search_issue).and_return(search_response)
+    allow(processor).to receive(:link_issue).and_return({ data: { id: node_id, link_id: 'attachment-1' } })
+  end
+
+  def build_private_note(content)
+    create(:message,
+           account: account,
+           inbox: inbox,
+           conversation: conversation,
+           sender: user,
+           message_type: :outgoing,
+           private: true,
+           content: content)
+  end
+
+  describe '#perform' do
+    context 'when the message is not a private note' do
+      it 'does no work' do
+        message = create(:message, account: account, inbox: inbox, conversation: conversation,
+                                   sender: user, message_type: :outgoing, private: false,
+                                   content: "see #{linear_url}")
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).not_to have_received(:linked_issues)
+        expect(processor).not_to have_received(:search_issue)
+        expect(processor).not_to have_received(:link_issue)
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when the sender is not a User' do
+      it 'does no work' do
+        contact = create(:contact, account: account)
+        message = create(:message, account: account, inbox: inbox, conversation: conversation,
+                                   sender: contact, message_type: :incoming, private: true,
+                                   content: "see #{linear_url}")
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).not_to have_received(:link_issue)
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when the private note has no Linear URL' do
+      it 'does no work' do
+        message = build_private_note('just a regular note with no link')
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).not_to have_received(:link_issue)
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when the issue identifier is already linked from this conversation' do
+      it 'skips silently' do
+        message = build_private_note("see #{linear_url}")
+        allow(processor).to receive(:linked_issues).and_return(
+          { data: [{ 'id' => 'attachment-prev', 'issue' => { 'id' => node_id, 'identifier' => identifier } }] }
+        )
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).not_to have_received(:search_issue)
+        expect(processor).not_to have_received(:link_issue)
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when Linear search returns no exact match for the identifier' do
+      it 'does not link' do
+        message = build_private_note("see #{linear_url}")
+        allow(processor).to receive(:search_issue).with(identifier).and_return(
+          { data: [{ 'id' => 'other', 'identifier' => 'OTHER-1', 'url' => 'https://linear.app/chatwoot/issue/OTHER-1' }] }
+        )
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).not_to have_received(:link_issue)
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when the matching issue belongs to a different Linear workspace' do
+      it 'does not link' do
+        message = build_private_note("see #{linear_url}")
+        allow(processor).to receive(:search_issue).with(identifier).and_return(
+          { data: [{ 'id' => node_id, 'identifier' => identifier,
+                     'url' => 'https://linear.app/other-workspace/issue/CW-1234' }] }
+        )
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).not_to have_received(:link_issue)
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when Linear search returns an error' do
+      it 'does not link' do
+        message = build_private_note("see #{linear_url}")
+        allow(processor).to receive(:search_issue).with(identifier).and_return({ error: 'boom' })
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).not_to have_received(:link_issue)
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when link_issue returns an error' do
+      it 'does not post the activity message' do
+        message = build_private_note("see #{linear_url}")
+        allow(processor).to receive(:link_issue).and_return({ error: 'nope' })
+
+        described_class.new(account: account, message: message).perform
+
+        expect(Linear::ActivityMessageService).not_to have_received(:new)
+      end
+    end
+
+    context 'when the private note contains a Linear URL' do
+      it 'links the issue and posts an activity message' do
+        message = build_private_note("Found it: #{linear_url}")
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).to have_received(:link_issue).with(
+          a_string_matching(%r{/conversations/#{conversation.display_id}\z}),
+          node_id,
+          anything,
+          user
+        )
+        expect(Linear::ActivityMessageService).to have_received(:new).with(
+          conversation: conversation,
+          action_type: :issue_linked,
+          user: user,
+          issue_data: { id: identifier }
+        )
+        expect(activity_service).to have_received(:perform)
+      end
+
+      it 'links only the first Linear URL when multiple are present' do
+        second_url = 'https://linear.app/chatwoot/issue/CW-9999'
+        message = build_private_note("see #{linear_url} and #{second_url}")
+
+        described_class.new(account: account, message: message).perform
+
+        expect(processor).to have_received(:search_issue).with(identifier).once
+        expect(processor).not_to have_received(:search_issue).with('CW-9999')
+      end
+    end
+  end
+end