chore(docs): Add atarashi week4 report

docs/2025/atarashi-enhancement/updates/2025-06-25.md

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+---
+title: Week 4
+author: Rajul Jha  
+tags: [gsoc25, Atarashi]
+---
+
+<!--  
+SPDX-License-Identifier: CC-BY-SA-4.0  
+SPDX-FileCopyrightText: 2025 Rajul Jha <rajuljha49@gmail.com>  
+-->
+
+# Week 4
+
+*(June 17, 2025 - June 25, 2025)*
+
+## Meeting 1
+
+*(June 25, 2025)*
+
+## Attendees
+
+* [Rajul Jha](https://github.com/rajuljha)
+* [Shaheem Azmal M MD](https://github.com/shaheemazmalmmd)
+* [Ayush](https://github.com/hastagAB)
+* [Sushant](https://github.com/its-sushant)
+
+## Discussions
+
+* Demonstrated the working **KeywordAgent**, built using `SRINGS.in` from the Nomos agent.
+* Shared the **evaluator script results** tested on NomosTestFiles — yielded **~99.5% accuracy**.
+* Debugged cases with true negatives and realized the need for **additional keyword sources**.
+* Finalized a **two-stage filtering architecture** for license detection pre-check.
+* Walked through **code improvements and refactoring** done on the Atarashi base code.
+
+## KeywordAgent Implementation
+
+Implemented a rule-based keyword detection agent using regex patterns derived from `SRINGS.in`. Keywords included:
+
+```yaml
+acknowledg(e|ement|ements)?
+agreement
+as[\s-]is
+copyright
+damages
+deriv(e|ed|ation|ative|es|ing)
+redistribut(e|ion|able|ing)?|distribut(e|ion|able|ing)?
+free software
+grant
+indemnif(i|y|ied|ication|ying)?
+intellectual propert(y|ies)?
+[^e]liabilit(y|ies)?
+licencs?
+mis[- ]?represent
+open source
+patent
+permission
+public[\s-]domain
+require(s|d|ment|ments)?
+same terms
+see[\s:-]*(https?://|file://|www.|[A-Za-z0-9._/-]+)
+source (and|or)? ?binary
+source code
+subject to
+terms and conditions
+warrant(y|ies|ed|ing)?
+without (fee|restrict(ion|ed)?|limit(ation|ed)?)
+severability clause
+```
+
+
+## Evaluation Results
+
+* Ran the KeywordAgent on **NomosTestFiles**.
+* Achieved **~99.5% accuracy**, confirming robustness of regex pattern matching.
+* Detected minor edge cases (true negatives) which informed the next steps for keyword expansion.
+
+## Code Improvements
+
+* Refactored parts of the Atarashi codebase:
+  * Applied Python best practices (docstrings, function decomposition, consistent naming).
+  * Improved error handling and logging in preprocessing and agent workflows.
+
+- **Commit:** https://github.com/fossology/atarashi/compare/master...rajuljha:atarashi:feat/newagent/Keyword
+
+## Two-Stage Detection Plan
+
+![image](/img/atarashi/atarashi-decision-tree.png)
+
+Decided on a layered pre-check system for Atarashi Scanner:
+
+1. **Stage 1:** Match against the **initial keyword list** (from SRINGS.in).
+2. **Stage 2:** If Stage 1 fails, match against **license shortnames** and **FOSSology license_ref** strings.
+3. If neither stage matches, the file is **skipped** from scanning.
+4. If either matches, it is **scanned using Atarashi**.