Hallucination Is a Post-Training Bug, Not a Knowledge Gap
If RLHF systematically drops the rare-but-correct modes that multi-step automation depends on, then scaling pretraining cannot fix agent reliability — the fix has to live in the post-training objective, the decoding policy, or the harness. Every reliability roadmap that begins with 'wait for a better model' is therefore misallocated, and the teams that win will be the ones that treat the aligned model as one unreliable subsystem and build verifiers, reversibility, and step checkpoints around it.
AngleReframe hallucination from a capability ceiling to an optimization artifact, then trace the concrete engineering consequences for anyone shipping agents.
Source video ↗The Stakes-and-Catch Screen: A Pre-Deployment Gate for Agent Projects
The assistance/automation boundary is not a domain question but a ratio question — undetected error cost times model error probability versus human catch rate — and projects that fail that screen should not be 'fixed' with a better prompt or a bigger model but re-architected as assistive, or given a verifier that supplies the missing catch. Stated this way, the boundary becomes a falsifiable scoring function that can be run over a backlog before a single line of agent code is written.
AngleTurn a qualitative talk distinction into an operational, numeric pre-deployment screen, and show what re-architecture looks like when a project fails it.
Source video ↗Your Coding Agent's Safety Comes From Git, Not From the Model
Coding agents appear to work because version control supplies exactly the human-in-the-loop catch that the RLHF objective assumes exists — cheap inspection, cheap rollback, diff-level review. That means attribute their success to the substrate rather than the model, expect reliability to collapse the moment an agent takes irreversible actions, and treat building inspection/rollback primitives as the prerequisite for extending agents beyond reversible work.
AngleAttribute agent reliability to its environment and invert the usual 'the model got better at coding' narrative.
Source video ↗Bitter Lesson, Extended: Task Choice Beats Data Beats Compute
If misaligned objectives cannot be rescued by scale, then the competitive variable in applied AI is task specification, not model access — and lab-level outcome differences should be read as differences in north-star clarity rather than capability ceilings. The practical corollary is that investment in evaluation targets and task definition has higher leverage than additional training compute, and picking the wrong target makes every extra FLOP marginal or harmful.
AngleExtend the bitter lesson into a hierarchy and argue for reallocating applied-AI budget from compute to task definition and evaluation design.
Source video ↗ModeDrop Probe
beyond-evalsFor a fixed base model and task suite, post-training on a preference proxy measurably collapses output entropy on reasoning traces and reduces pass@k on rare-but-correct solutions, and the size of this collapse predicts end-to-end failure rate on multi-step tasks better than benchmark accuracy does.
Proof of conceptEvaluate a base model and its post-trained variant on the same executable multi-step task suite; compute per-task output-distribution divergence, entropy of reasoning traces, and pass@k at high k for tasks whose correct solution requires an unusual path; regress task failure rate on the collapse metrics.
MeasurementCorrelation between post-training-induced entropy collapse / pass@k drop on rare modes and observed end-to-end task failure rate; whether accuracy on standard benchmarks stays flat while rare-mode pass@k falls.
Source video ↗Horizon Budget Calculator
movement-labAgent end-to-end success decays as a multiplicative function of per-step correctness, so inserting a verifier every N steps yields superlinear reliability gains versus marginally improving per-step quality, and a maximum viable horizon length can be predicted in advance for a target end-to-end success rate.
Proof of conceptInstrument an agent runtime to log per-step success across traces of varying length; fit per-step success probability; predict end-to-end success for lengths L; then compare predicted versus observed success for runs with and without periodic verifier checkpoints.
MeasurementFit quality of the exponential-decay model against observed success-vs-length curves; delta in end-to-end success rate per unit of added verification frequency versus per unit of per-step model improvement.
Source video ↗Stakes-and-Catch Scorer
gatehouseA task score over error cost, human catch rate, reversibility, and verifiability predicts the success/failure of deployed generative AI use cases, and misclassified cases are exactly those that should have been re-architected as assistive or verifier-gated.
Proof of conceptScore a portfolio of internal or publicized AI deployments on the four axes, bin by assistive versus automated as deployed, and compare the score distribution against reported outcomes.
MeasurementDiscriminative power (e.g., AUC or precision/recall) of the score for predicting deployment success versus a baseline that classifies only by domain or model capability.
Source video ↗Split-Policy Router
newRouting candidate generation to a mode-covering path and using the preference-tuned model only for the final user-facing surface raises success on tasks where rare correct modes dominate, compared to repeatedly sampling the aligned model.
Proof of conceptBuild a two-policy agent: an exploration stage that samples a less-aligned or higher-temperature model for candidates, and a serving stage that uses the aligned model to select and express the answer. Compare against an aligned-model-only baseline on the same rare-mode task suite.
MeasurementTask success rate on rare-mode-dominated tasks at matched token/compute budget; diversity of candidate sets pre-filter; number of correct-but-low-probability solutions surfaced per run.
Source video ↗