feat: add web_search and fetch_url research tools (#2)

- Add ResearchTools class in gitea/tools/research_tools.py
  - web_search: DuckDuckGo HTML search, no API key required
  - fetch_url: httpx-based URL fetcher with HTML stripping + truncation
- Wire both tools into planning_tools and coding_tools_list in dispatcher.py
- Add 19 unit tests covering all methods, error paths, and edge cases

---------

Co-authored-by: Michael <michael@example.com>
Reviewed-on: #2

core/dispatcher.py

@@ -6,6 +6,7 @@ from typing import Any
 from core.coding_agent import CodingAgent
 from core.queue import WorkItem
 from gitea.tools.coding_tools import CodingTools
+from gitea.tools.research_tools import ResearchTools
 from gitea.tools.gitea_tools import GiteaTools
 from gitea.client import GiteaClient
 from core.coding_prompt import CODING_AGENT_SYSTEM_PROMPT
@@ -98,6 +99,7 @@ class AgentDispatcher:
         workspace = WorkspaceManager()
         repo_path = workspace.get_repo_path(repo)
         coding_tools = CodingTools(str(repo_path))
+        research_tools = ResearchTools()
 
         planning_tools: list[Any] = [
             self._tools.get_issue,
@@ -114,6 +116,8 @@ class AgentDispatcher:
             coding_tools.grep_search,
             coding_tools.get_working_directory,
             coding_tools.run_command,
+            research_tools.web_search,
+            research_tools.fetch_url,
         ]
 
         coding_tools_list: list[Any] = [
@@ -147,6 +151,8 @@ class AgentDispatcher:
             coding_tools.run_command,
             coding_tools.grep_search,
             coding_tools.get_working_directory,
+            research_tools.web_search,
+            research_tools.fetch_url,
         ]
 
         results: list[str] = []
@@ -207,12 +213,17 @@ class AgentDispatcher:
                         logger.info(f"Starting Planning Phase for {item.task_type} #{item.task_number} (attempt {attempt})")
                         planning_mission = (
                             f"PHASE 1: PLANNING PHASE\n\n"
-                            f"Your task is to analyze the repository structure and create a detailed implementation plan.\n"
+                            f"Your task is to research the problem, analyse the repository structure, and produce a detailed implementation plan.\n"
                             f"Original Mission details:\n{base_mission}\n\n"
                             f"CRITICAL RULES:\n"
                             f"1. You are ONLY generating an implementation plan. DO NOT write files, DO NOT edit files, DO NOT commit, DO NOT push, and DO NOT create branches or PRs.\n"
-                            f"2. Explore the codebase using read_file, list_files, grep_search, or run_command (for read-only queries like find/grep).\n"
-                            f"3. Output your final plan clearly, describing the exact changes to be made and which files to modify.\n"
+                            f"2. RESEARCH FIRST (mandatory before writing the plan):\n"
+                            f"   - Use web_search to find relevant documentation, known solutions, library APIs, error explanations, and best practices.\n"
+                            f"   - Use fetch_url to read specific documentation pages, changelogs, or Stack Overflow answers in full.\n"
+                            f"   - Use web_search with time_range='month' or time_range='year' for recency-sensitive queries.\n"
+                            f"   - Use web_search with categories='it' for technical/programming topics.\n"
+                            f"3. EXPLORE the codebase using read_file, list_files, grep_search, or run_command (read-only queries like find/grep).\n"
+                            f"4. Output your final plan clearly, describing the exact changes to be made and which files to modify.\n"
                         )
                         planning_agent = CodingAgent(self._model_name)
                         plan = await planning_agent.run_with_tools(planning_mission, planning_tools)
@@ -225,7 +236,10 @@ class AgentDispatcher:
                             f"You must now implement the changes based on the following plan generated in Phase 1:\n"
                             f"--- PLAN ---\n{plan}\n--- PLAN END ---\n\n"
                             f"Original Mission details:\n{base_mission}\n\n"
-                            f"Follow the repository workflow to make the changes, verify them, commit, push, and create a PR.\n"
+                            f"AVAILABLE RESEARCH TOOLS (use whenever uncertain about an API, syntax, or behaviour):\n"
+                            f"  - web_search(query, time_range, categories) — search the web via SearXNG/DuckDuckGo\n"
+                            f"  - fetch_url(url) — read any documentation page, README, or Stack Overflow answer in full\n\n"
+                            f"Follow the repository workflow: implement changes, run verification, commit, push, and create a PR.\n"
                         )
                         coding_agent = CodingAgent(self._model_name)
                         response = await coding_agent.run_with_tools(coding_mission, coding_tools_list)