
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given the function $f(x) = (x^2 - a)e^{1-x}$, where $a \in \mathbb{R}$:
(Ⅰ) Discuss the monotonicity of the function $f(x)$;
(Ⅱ) If $f(x)$ has two extreme points, $x_1$ and $x_2$ ($x_1 < x_2$), it always holds that $x_2f(x_1) \leq \lambda \left[ f'(x_1) - a(e^{1-x_1} + 1) \right]$ (where $f'(x)$ is the derivative of $f(x)$). Find the value of the real number $\lambda$.

Present the answer in LaTex format: \boxed{Your answer}
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