In high-risk text interactions, a system may need to estimate whether the current speaker is likely to be a minor before applying age-conditioned safeguards. Many text-based dialogue systems lack strong identity signals such as account information, verified identity, facial data, or device data, and must rely on weak cues that emerge across multiple turns. We formulate implicit minor detection under weak identity information as a high-risk user-attribute inference task and propose a constrained framework comprising a large language model, a Harness, and a Maker-Checker protocol. The framework controls when inference is invoked, requires structured dialogue-linked evidence, and subjects validation-selected Harness revisions to version-level review. On a controlled Chinese benchmark comprising 8,328 multi-turn dialogues, our method improves average precision and minor-class F1 by 7.60 and 6.37 percentage points, respectively, over direct inference using the same LLM family.
Figures & tables
Figure 1: Adjacent approaches leave a weak-identity gap. Platform age assurance depends on strong identity signals; static single-turn profiling loses cross-turn and speaker-binding context; content-safety safeguards assess content risk rather than the speaker’s likely age.
Figure 2: Overview of the constrained implicit-minor-detection framework. Runtime inference separates trigger routing, contextual support, structured evidence, and source-constrained decisions. During development, validation errors and recent candidate outcomes guide restricted Harness revisions; the gate either promotes a candidate or retains the incumbent, and the selected version is accompanied by Maker–Checker review materials.
Method
AP ↑
Minor F1 ↑
Minor precision ↑
Minor recall ↑
Chinese-RoBERTa-wwm-ext
0.8154±0.0093
0.6544±0.0179
0.6743±0.0186
0.6359±0.0222
Gemini Direct
0.8815±0.0006
0.8561±0.0010
0.8317±0.0019
0.8820±0.0007
Aegis-Guard FT
0.8424±0.0045
0.6640±0.0121
0.8963±0.0200
0.5278±0.0215
Aegis-Guard FT + Harness
0.8744±0.0131
0.7851±0.0178
0.8541±0.0113
0.7271±0.0331
Ours
0.9574±0.0062
0.9198±0.0015
0.9360±0.0122
0.9044±0.0109
Table 1: Held-out main-task results on 1,665 dialogues over three runs. Values are mean ± sample standard deviation.
Variant
Acc. ↑
AP ↑
F1 m ↑
Prec. m ↑
Rec. m ↑
Ours (selected Harness)
0.9211±0.0019
0.9574±0.0062
0.9198±0.0015
0.9360±0.0122
0.9044±0.0109
Ours (initial Harness)
0.8975±0.0050
0.9429±0.0036
0.8971±0.0048
0.9011±0.0073
0.8932±0.0036
w/o contextual support
0.8907±0.0033
0.9246±0.0065
0.8941±0.0037
0.8672±0.0011
0.9228±0.0077
w/o evidence traceability
0.9045±0.0026
0.9434±0.0028
0.9002±0.0029
0.9434±0.0015
0.8607±0.0042
Table 2: Held-out main-task ablations over three runs. Values are mean ± sample standard deviation.
Description
Prec.
Rec.
F1
Initial
0.831±0.012
0.715±0.042
0.768±0.019
Selected
0.823±0.031
0.861±0.043
0.841±0.006
Table 3: Initial and development-selected trigger descriptions on the held-out trigger test split over three runs (mean ± sample standard deviation).
Figure 3: Candidate minor-F1 change relative to the current incumbent for the two full-budget validation runs. Filled circles denote promoted candidates and crosses denote rejected candidates.
Appendix figures & tables11 assets
Supplementary material from the paper’s appendix.
Appendix
Evaluation surface
Total
Development
Held-out
Primary role
Main recognition benchmark
8,328
5,830 train + 833 validation
1,665 test
Speaker-level minor recognition
Trigger-Eval
480
288 development
192 test
Invocation-boundary evaluation
Human challenge set
40
—
40 shared items
Difficulty and disagreement reference
Appendix
Table S1: Evaluation surfaces used in the paper. Trigger-Eval and the human challenge set are separate from recognition training and retrieval.
Seed
Δ AP [95% CI]
Δ F1 m [95% CI]
McNemar p
Selected vs. Gemini Direct
42
.0795[.0601,.0999]
.0644[.0460,.0841]
3.16×10−13
43
.0686[.0491,.0891]
.0613[.0435,.0784]
2.97×10−12
44
.0798[.0614,.0986]
.0655[.0475,.0823]
5.84×10−14
Selected vs. Initial Harness
42
.0212[.0067,.0347]
.0279[.0115,.0436]
.000327
Appendix
Table S2: Paired uncertainty for the main shared-model comparison and the initial-to-selected Harness comparison. Intervals are computed separately for each archived run on the shared 1,665-item test set.
Seed
Prop.
Prom.
Rej.
F1: initial → selected
42
10
5
5
.9009→.9455
43
10
5
5
.9067→.9652
44
5
1
4
.9168→.9483
All
25
11
14
—
Appendix
Table S3: Summary of main-task validation evolution. Rejected candidates do not replace the incumbent.
Version
Decision
F1
Recall
Precision
v0
initial incumbent
.9009
.8197
1.0000
v1
promote
.9223
.8558
1.0000
v2
promote
.9280
.8678
.9972
v3
reject
.9223
.8558
1.0000
v4
promote
.9320
.8726
1.0000
v5
reject
.9223
.8558
1.0000
Appendix
Table S4: Main-task validation trajectory for seed 42. A rejected candidate leaves the incumbent unchanged.
Version
Decision
F1
Recall
Precision
v0
initial incumbent
.9067
.8293
1.0000
v1
promote
.9138
.8413
1.0000
v2
reject
.9055
.8293
.9971
v3
promote
.9294
.8702
.9972
v4
reject
.9110
.8365
1.0000
v5
reject
.9294
.8702
.9972
Appendix
Table S5: Main-task validation trajectory for seed 43. A rejected candidate leaves the incumbent unchanged.
Version
Decision
F1
v0
initial incumbent
.9168
v1
reject
.9156
v2
promote
.9483
v3
reject
.9430
v4
reject
.9388
v5
reject
.9430
Appendix
Table S6: Main-task validation trajectory for seed 44. The run stops after rounds 3–5 yield three consecutive non-promotions.
Seed
P/R
Initial F1
Selected F1
Recall
FTR
42
3/4
.7925
.8667
.9028
.1806
43
3/5
.8145
.8763
.8611
.1042
44
3/4
.7820
.8776
.8958
.1458
Appendix
Table S7: Trigger-description development trajectories. P/R denotes promoted/rejected proposals; FTR is the development false-trigger rate.
Individual metric
Mean
SD
95% CI
Accuracy
.7255
.1031
[.6970,.7530]
Minor F1
.7275
.1130
[.6956,.7570]
Appendix
Table S8: Distribution of individual participant performance over all 40 challenge items. Confidence intervals use respondent bootstrap resampling.
Stratum
Items
Human accuracy
Easy
10
.834
Hard
15
.657
Adversarial
10
.808
Boundary
5
.548
Appendix
Table S9: Mean item-level human accuracy by construction stratum.
Reference
Coverage
Accuracy
Minor F1
Mean individual
1.00
.7255
.7275
Strict majority
.95
.8684
.8571
Seed 42
1.00
.6000
.5556
Seed 43
1.00
.7750
.7568
Seed 44
1.00
.6500
.5882
Appendix
Table S10: Human and system references on the shared challenge set. Strict-majority metrics use the 38 non-tied items; all other rows use all 40 items.
Tie rule
Coverage
Accuracy
Minor F1
Abstain on 25–25
.95
.8684
.8571
Map both ties to adult
1.00
.8250
.8108
Map both ties to minor
1.00
.8750
.8718
Appendix
Table S11: Sensitivity of strict-majority results to the two unresolved items. The primary analysis uses abstention.
Large language model (LLM) security has largely focused on role-playing jailbreaks, with less attention to what happens when a user asks an LLM to verify an identity claim through a test designed by the model itself. We study this behavior through a staged developer-identity experiment with ChatGPT, Claude, Qwen, Mistral, and Llama. All five models initially rejected the unsupported claim "I am your developer." Claude refused to conduct an identity test, while ChatGPT generated developer-oriented questions but maintained that answers could demonstrate knowledge, not identity. In contrast, Qwen and Mistral generated technical challenges, defined what counted as convincing evidence, evaluated detailed answers, and returned Verified without receiving any externally validated identity evidence. Llama similarly generated and evaluated a developer test, accepted the claimed identity, and subsequently made unsupported claims of access to internal runtime and deployment state. We call the model-generated verification procedure a Model-Issued Pseudo-Credential (MIPC) and the resulting unsupported identity judgment Conversational False Authentication (CFA). In each CFA case, the same model acted as challenge generator, evidence evaluator, and identity decision-maker, converting technical knowledge into supposed proof of identity. The accepted identities did not change the tested authorization boundaries, showing that false authentication and privilege escalation are distinct outcomes. These results identify self-issued authentication as a conversational security failure: authenticated identity must originate from an external security component, and model-generated dialogue must never create or modify identity or authorization state.
Autonomous systems increasingly rely on Large Language Models (LLMs) yet the safety infrastructure surrounding these models introduces latency and compute overhead. This limits utility in resource-constrained, time-critical deployments. Existing external guardrail models remain blind to the model's internal workings, creating a fundamental assurance gap. We ask: does the model already know when the content is harmful? We extract activations from LLaMA-3.1-8B and train lightweight MLP classifier probes (12.6M parameters) to detect harmful prompts. Evaluated on WildJailbreak, Beavertails, and AEGIS 2.0, our probes achieve F1 scores of 99%, 83%, and 84%, respectively competitive with 1000x larger guard models while cutting latency and compute costs.
Recent advances in large language models (LLMs) have made it increasingly difficult to distinguish human-written text from AI-generated content. Many existing detectors train supervised neural classifiers that achieve strong in-distribution performance but are often opaque and can degrade substantially under distribution shift. We present READER, a reasoning-enhanced AI text detector that outputs both a human/AI label and a structured rationale describing the evidence for its decision. A key component of our approach is READ, a curated supervision set of rationales and verdicts. We fine-tune an LLM on READ to build READER, which reasons before detecting at inference time. Despite having only 1.5B parameters, READER consistently outperforms existing detectors as well as prompted, high-capacity LLM baselines (GPT-5.2, Gemini-3-Pro, and DeepSeek-V3.2), which are 100 to 1000 times larger in scale.
Pingfan Su, Kai Ye, Shijin Gong +4
Department of Statistics, London School of Economics and Political Science · School of Management, University of Science and Technology of China · School of Mathematics, University of Birmingham