In multi-turn conversations, large language models typically condition on the full conversation history: both past user prompts and assistant responses. We revisit this design choice by comparing full-context prompting to four alternative, substantially-reduced context configurations. Analyzing in-the-wild multi-turn conversations across three open reasoning and one state-of-the-art model, we find that response quality is largely preserved under aggressive context filtering: replacing all prior assistant turns with one-sentence summaries or keeping only the most recent user--assistant exchange often matches storing full context in performance while using roughly 8x less context. To understand this result, we observe that a substantial fraction of user turns (36.4%) in multi-turn conversations are self-contained and that many follow-up turns can be addressed by seeing only the immediately preceding user--assistant exchange. Furthermore, we find that when models condition on their own past responses, this can lead to context pollution, a phenomenon in which reasoning errors, hallucinations, or stylistic artifacts propagate across turns. Motivated by these findings, we design a context-filtering approach that selectively omits the assistant-side history. Taken together, these findings suggest moving away from storing full dialogue transcripts and instead retaining only what is relevant.
Figures & tables
Figure 1: Real example of overrelying on irrelevant context. In Turn 2, the user requests UMAP clustering code. In Turn 5, the user says, “use t-SNE instead.” Left: When the previous assistant response remains in context, the model incorrectly carries over the Jaccard metric from UMAP into the t-SNE implementation, introducing a bug. Right: Without the previous response in context, the model generates correct t-SNE code.
Figure 2: Pairwise win rates between Full Context (FC) prompting and three reduced-context configurations across four models (Qwen3-4B, DeepSeek-R1-Distill-Llama-8B, GPT-OSS-20B, and GPT-5.2), evaluated on the Quality and On-Topic dimensions. Top row: FC vs. summarized assistant history (SUM), where each prior assistant response is replaced with a one-sentence summary. Second row: FC vs. Last Turn Only (LT), which retains only the most recent user–assistant round. Third row: FC vs. Assistant Omitted (AO), which retains all user turns but replaces assistant responses with a placeholder. Bottom row: FC vs. Delete Everything (DE), which provides only the current user prompt. Error bars indicate binomial proportion 95% confidence intervals.
Figure 3: Three example conversations on WildChat illustrating different types of follow-ups. Left: the user provides feedback that is concrete enough that the model can respond from scratch using the previous user turn and the updated specifications alone. Middle: the follow-ups reference specific parts in past assistant turns, making it necessary to see the referenced assistant turn. Right: the follow-up references a prior user turn without concrete feedback; no assistant history is necessary.
Figure 4: Left: Distribution of conversation rounds referenced by user prompts from round 2 onward, across 150 WildChat conversations. The X-axis represents the number of rounds back from the current round that a given prompt references. The red stem at 0 indicates prompts that are self-contained (no prior rounds referenced). Middle: Mean cumulative context length across conversations on WildChat as a function of conversation round, comparing Full Context, Assistant Omitted, Last Turn Only , and Summarized context. Shaded band shows ± 2 standard errors. Right: The number of conversations that can be answered using a 5K-token budget as a function of conversation round.
Figure 5: Left: Accuracy (%) on multi-turn GSM8K under Full Context (FC) and Assistant Omitted (AO) context. Right: Confusion matrices showing the number of problems answered correctly across models and context configurations.
Assistant-response History
Filler History
Category
Count
Conf.
Count
Conf.
Intent Override
39
0.74
0
0.96
Incorrect Code Carryover
30
0.77
0
0.95
Factual Hallucination Carryover
27
0.75
0
0.95
Reasoning Trace Carryover
6
–
–
–
Formula Carryover
1
–
–
–
Table 1: Prevalence of context pollution instances across 729 responses generated by GPT-5.2 on WildChat conversations, under the original history and a history in which assistant-side responses are replaced with length-matched filler text. Confidence values indicate the LLM annotator’s average confidence across instances in that category.
Figure 6: Ratio of adaptive wins to full-context-only wins vs. mean token count (in thousands) for operating points obtained by sweeping the decision rule’s threshold τ and cost weight λ . The green triangle marks a heuristic that omits assistant responses on all turns categorized as “New Asks.”
Appendix figures & tables8 assets
Supplementary material from the paper’s appendix.
Appendix
Config
Qwen3-4B
DeepSeek-R1
GPT-OSS-20B
GPT-5.2
Sum
≥
≥
≥
≥
LT
≥
≥
∼
∼
AO
∼
∼
DE
Appendix
Table 2: On-Topic: comparison of reduced-context configurations against Full Context (FC), per model. ≥ indicates that reduced context performs significantly better than or is statistically indistinguishable from FC (95% CIs overlap); ∼ indicates that the win-rate gap is within 10pp.
Config
Qwen3-4B
DeepSeek-R1
GPT-OSS-20B
GPT-5.2
Sum
≥
≥
≥
LT
≥
≥
∼
AO
∼
DE
Appendix
Table 3: Quality: comparison of reduced-context configurations against Full Context (FC), per model. ≥ indicates that the reduced context performs significantly better than or is statistically indistinguishable from FC (95% CIs overlap); ∼ indicates that the win-rate gap is within 10pp.
Figure 8: Pairwise win rates by prompt category (new ask, follow up with feedback, follow up without feedback) for Qwen3-4B (top) and GPT-5.2 (bottom), comparing Full-Context (FC) and Assistant-Omitted (AO) responses. Stars indicate statistically significant differences. Error bars indicate binomial proportion 95% confidence intervals.
Figure 9: Pairwise win rates between Full Context (FC) and three reduced-context configurations across all four models (Qwen3-4B, DeepSeek-R1-Distill-Llama-8B, GPT-OSS-20B, and GPT-5.2), evaluated on the Quality and On-Topic dimensions. Top row: FC vs. Last Turn Only (LT), which retains only the most recent user–assistant round. Middle row: FC vs. Assistant Omitted (AO), which retains all user turns but replaces assistant responses with a placeholder. Bottom row: FC vs. Delete Everything (DE), which provides only the current user prompt. Error bars indicate binomial proportion 95% confidence intervals.
Figure 10: Pairwise win rates between Full Context (FC) and three reduced-context configurations across all four models (Qwen3-4B, DeepSeek-R1-Distill-Llama-8B, GPT-OSS-20B, and GPT-5.2), evaluated on the Quality and On-Topic dimensions. Top row: FC vs. Last Turn Only (LT), which retains only the most recent user–assistant round. Middle row: FC vs. Assistant Omitted (AO), which retains all user turns but replaces assistant responses with a placeholder. Bottom row: FC vs. Delete Everything (DE), which provides only the current user prompt. Error bars indicate binomial proportion 95% confidence intervals.
Figure 11: Pairwise win rates between Full-Context (FC) and Assistant-Omitted (AO) responses when the judge evaluates only final answers. Compare with Fig. 9 , in which the judge receives both thinking traces and final answers.
Model
Fraction of Turns ≥ FC
Tokens Saved
GPT-5.2 (self-generated context)
0.916
37.7%
Qwen3-4B (self-generated context)
0.915
49.2%
DeepSeek-R1 (historical context)
0.875
49.4%
GPT-OSS-20B (historical context)
0.927
43.5%
Appendix
Table 4: Fraction of turns meeting or exceeding the full-context (FC) baseline, and the corresponding token savings, across four models. Parentheses labels indicate whether the conversation history was self-generated or drawn from historical logs.
Feature
Coef.
SE
95% CI
PromptPC3
−0.2003
0.1200
[−0.4355,0.0350]
HistoryPC17
−0.1606
0.1056
[−0.3677,0.0464]
HistoryPC2
−0.1412
0.1320
[−0.1176,0.4000]
category_new_ask
−0.1308
0.1098
[−0.3460,0.0843]
PromptPC24
−0.0963
0.0941
[−0.0881,0.2807]
HistoryPC26
−0.0920
0.0880
[−0.0805,0.2644]
Appendix
Table 5: Logistic regression coefficients with 95% confidence intervals. This table displays the 20 features with the largest absolute coefficient magnitudes.