Update README.md

README.md

@@ -38,42 +38,60 @@ print(obs.code_snippet)
 - `POST /mcp` – minimal MCP endpoint
 
 ## Tasks
-Easy (null‑checks, simple logic errors)
-#	Bug ID	Description	How to inject
-1	null_check	Missing if key in dict: guard	AST: remove if‑statement
-2	simple_typo	Variable name misspelled (users → usres)	AST: rename variable
-3	string_index	Indexing string with wrong index (off‑by‑one)	AST: change constant in index
-4	default_value	Not providing a default in dict.get()	AST: replace dict[key] with dict.get(key) … but wrongly
-5	empty_return	Function returns None in a branch that should return something	AST: insert return None or delete a return
-Medium (off‑by‑one, loop logic, simple arithmetic)
-#	Bug ID	Description	How to inject
-6	off_by_one	range(x) → range(1, x-1) (skips first and last)	AST: modify range args
-7	loop_skip	for i in range(len(arr)): missing last element because of off‑by‑one	AST: change range length
-8	sign_error	sum += item replaced with sum -= item	AST: swap Add/Sub
-9	swap_args	Calling a function with arguments swapped	AST: swap arg order
-10	uninitialised_var	Using a variable before assignment in a loop	AST: remove assignment line
-Hard (division‑by‑zero, floating‑point, edge‑case handling)
-#	Bug ID	Description	How to inject
-11	division_by_zero_empty	Missing check for empty list before averaging	AST: remove the if not data: guard
-12	division_by_zero_zero	Integer division where denominator can be zero	AST: remove a denominator‑checking statement
-13	float_precision	Using integer division // instead of / for average	AST: change operator
-14	abs_usage	Forgetting abs() when comparing differences	AST: remove abs() call
-15	round_error	Rounding too early causing precision loss	AST: insert round() incorrectly
-Harder (race conditions, missing atomic operations)
-#	Bug ID	Description	How to inject
-16	missing_lock	Shared counter accessed without a lock	Template: remove with lock: from code
-17	double_lock	Acquiring the same lock twice (deadlock risk)	Template: add extra lock.acquire()
-18	global_nonatomic	Compound assignment x = x + 1 instead of atomic +=	AST: modify assignment node
-19	thread_safe_list	Appending to a list from multiple threads without lock	Template: remove lock around list operation
-20	volatile_read	Reading a shared flag outside a lock	Template: remove synchronization block
-Hardest (deadlock, ordering, complex concurrency)
-#	Bug ID	Description	How to inject
-21	deadlock_order	Lock A then lock B in one thread, opposite in another	Template: swap lock acquisition order
-22	nested_lock_timeout	Not using a timeout when acquiring locks, causing hang	Template: replace acquire() with acquire(blocking=True) without timeout
-23	fork_join	Starting threads and not waiting for them to finish (missing join())	AST: remove thread.join()
-24	mutex_release	Releasing a mutex in one thread that was locked by another	Template: wrong release logic
-25	race_on_init	Initializing a shared resource after threads have started	Template: move initialization after thread creation
+## 🐛 Bug Taxonomy (25 bugs across 5 difficulty levels)
 
+The **RedTeam** randomly selects one bug from the current difficulty level at the start of every episode.  
+Your agent must figure out what’s broken, gather evidence, and convince the simulated author – or it won’t stick.
+
+### 🟢 Easy – Null‑Checks & Simple Logic Errors
+
+| # | Bug ID | What’s wrong | Injection method |
+|---|--------|--------------|------------------|
+| 1 | `null_check` | Missing `if key in dict:` guard → KeyError | AST: remove the if‑statement |
+| 2 | `simple_typo` | Misspelled variable `users` → `usres` | AST: rename variable |
+| 3 | `string_index` | String index shifted by +1 | AST: change constant in index |
+| 4 | `default_value` | `dict.get(key)` used without a fallback | AST: replace `dict.get(key)` with `dict[key]` |
+| 5 | `empty_return` | Function returns `None` prematurely | AST: insert `return None` early |
+
+### 🟡 Medium – Off‑By‑One, Loop Logic & Simple Arithmetic
+
+| # | Bug ID | What’s wrong | Injection method |
+|---|--------|--------------|------------------|
+| 6 | `off_by_one` | `range(x)` becomes `range(1, x-1)` – skips first & last | AST: modify range arguments |
+| 7 | `loop_skip` | `range(len(arr))` becomes `range(len(arr)-1)` – misses last element | AST: change range length |
+| 8 | `sign_error` | `sum += item` turned into `sum -= item` | AST: swap Add / Sub |
+| 9 | `swap_args` | Function arguments swapped | AST: swap first two arguments |
+|10 | `uninitialised_var` | Variable used before assignment in a loop | AST: remove the assignment statement |
+
+### 🟠 Hard – Division‑By‑Zero, Floating‑Point & Edge Cases
+
+| # | Bug ID | What’s wrong | Injection method |
+|---|--------|--------------|------------------|
+|11 | `division_by_zero_empty` | Empty‑list guard removed before averaging | AST: delete `if not data:` |
+|12 | `division_by_zero_zero` | Denominator check removed | AST: remove the zero‑check |
+|13 | `float_precision` | True division `/` replaced by integer division `//` | AST: change Div → FloorDiv |
+|14 | `abs_usage` | `abs()` call removed when comparing differences | AST: delete `abs()` wrapper |
+|15 | `round_error` | `round()` placed too early, causing precision drift | AST: inject `round()` prematurely |
+
+### 🔴 Harder – Race Conditions & Atomicity Bugs
+
+| # | Bug ID | What’s wrong | Injection method |
+|---|--------|--------------|------------------|
+|16 | `missing_lock` | Shared counter incremented without a lock | Template: remove `with lock:` |
+|17 | `double_lock` | Acquiring the same lock twice → deadlock risk | Template: add extra `lock.acquire()` |
+|18 | `global_nonatomic` | `count = count + 1` (read‑modify‑write) instead of `+=` | AST: modify assignment node |
+|19 | `thread_safe_list` | List append across threads without synchronisation | Template: remove lock from list operation |
+|20 | `volatile_read` | Shared flag read outside a lock → stale value | Template: remove synchronisation block |
+
+### ⚫ Hardest – Deadlocks, Ordering & Complex Concurrency
+
+| # | Bug ID | What’s wrong | Injection method |
+|---|--------|--------------|------------------|
+|21 | `deadlock_order` | Locks acquired in opposite order in two threads | Template: swap lock order |
+|22 | `nested_lock_timeout` | `lock.acquire()` without a timeout → permanent hang | Template: remove timeout logic |
+|23 | `fork_join` | Thread started but not joined (`join()` missing) | AST: remove `thread.join()` |
+|24 | `mutex_release` | Lock released by a thread that never acquired it | Template: incorrect release logic |
+|25 | `race_on_init` | Shared resource initialised after threads have started | Template: move initialisation after `join()` |
 ## Deployment
 
 ```bash