What Drives LLM Self-Reflection? A Controlled Ablation of Uncertainty Routing in Armed Conflict Forecasting A controlled ablation of six conditions in LLM self-reflection for armed conflict forecasting finds that typed action routing, not diagnostic scaffolding or taxonomy vocabulary, drives performance gains, with F1 improving from 0.296 to 0.379 (ΔF1 = +0.075) and a significant overall gain over the single-shot baseline (ΔF1 = +0.101, 95% CI [+0.020, +0.185]). The study, posted on arXiv (2608.12322v1), replicates the vocabulary-routing decomposition on GPT-4o, confirming that action routing provides significant gains (p = 0.025) while taxonomy vocabulary adds no significant value (p = 0.773). Gains concentrate on structurally novel conflicts such as Myanmar (F1: 0.000 → 0.353) and Ukraine (0.167 → 0.500), identifying typed action routing as a promising design principle for metacognitive LLM forecasting agents. arXiv:2608.12322v1 Announce Type: new Abstract: Self-reflection is widely assumed to improve LLM reasoning, yet which component drives the gain remains poorly understood. We present a controlled six-condition ablation isolating four components of LLM self-reflection: evidence exposure, diagnostic scaffolding, taxonomy vocabulary, and action routing. Two precise null results converge on a single mechanism. First, structured diagnostic questions add no measurable value over unstructured reflection $\text{F1} = 0.296$ vs $0.297$, $p = 1.000$, 95\% CI $ -0.041, +0.040 $ . Second, presenting the full uncertainty taxonomy while collapsing the action space to a single generic action also adds no value $\Delta\text{F1} = +0.008$, overlapping 95\% CIs , ruling out taxonomy vocabulary as the mechanism. Typed action routing provides consistent directional gains $\text{F1} = 0.379$ vs $0.296$ ; the conservative estimate controlling for taxonomy vocabulary is $\Delta\text{F1} = +0.075$, and the overall gain over the single-shot baseline is significant by bootstrap CI $\Delta\text{F1} = +0.101$, 95\% CI $ +0.020, +0.185 $ . The vocabulary-routing decomposition replicates on GPT-4o: taxonomy vocabulary adds no significant value over generic reflection $p = 0.773$ , while action routing provides significant gains $p = 0.025$ , confirming the mechanism holds across backbones. Gains concentrate on structurally novel conflicts: in Myanmar $\text{F1}: 0.000 \rightarrow 0.353$ and Ukraine $0.167 \rightarrow 0.500$ , the vocabulary-only condition recovers no more than generic reflection while action routing breaks the degenerate prior. These findings identify typed action routing -- not diagnostic scaffolding or taxonomy vocabulary -- as a promising design principle for metacognitive LLM forecasting agents, while motivating larger-scale evaluation across conflict typologies.