A Survey of Agents in the Era of Experience: Skills, Harness, and Self- to Meta-Evolution

In the Era of Experience, agentic AI is no longer defined only by what a model can infer from static data, but by how a deployed system accumulates, organizes, and reuses experience from interaction. This survey studies experience-driven improvement in deployed agentic AI systems. We focus on the runtime harness as the infrastructure that captures traces, routes actions, exposes feedback, and governs mutable state. Around this infrastructure, we review how experience becomes reusable skill, persistent memory, verifiable environment feedback, trainable model behavior, and meta-level control. We then identify the remaining barriers to reliable improvement, including longitudinal evaluation, transfer, verification, and safety governance. Making agents smarter after deployment is therefore a trace-to-capability problem: the field must learn how to capture experience, assign it to the right update surface, verify its value, and preserve control as the system changes.

111
papers
9
paper chapters

Overview of the survey

Turning deployment experience into durable capability.

The survey's central claim is that making agents smarter after deployment is a trace-to-capability problem. A deployed system must capture interaction traces, compile them into usable experience, assign that experience to the right update surface, verify its value, and preserve control as the system changes.

Overview of the survey figure rendered from the LaTeX-referenced chapters PDF.
The paper moves from a harness-agent definition to external runtime adaptation, parameter-side consolidation, and the evaluation and safety requirements for turning deployment experience into durable capability.
01

Harness-agent definition

The runtime object is the model together with a mutable harness, a user-facing side, and an environment-facing side.

02

External runtime adaptation

Skills, memory, environments, tools, and other harness surfaces can change quickly, visibly, and reversibly during deployment.

03

Parameter-side consolidation

Stable deployment experience can later be promoted into model behavior, but only after the evidence is strong enough to justify a harder-to-reverse update.

04

Evaluation and safety conditions

A self-improving agent must be measured as a changing system, with retention, cost, attribution, and control tracked over time.

Harness as Experience Infrastructure

Runtime Adaptation Requires Experience Infrastructure

The first step is to name the object that can improve after deployment. The paper defines a deployed agentic AI system as a base model wrapped by a mutable harness, with user-facing and environment-facing sides that supply goals, actions, observations, tests, corrections, and operational state.

Harness as experience infrastructure figure rendered from the LaTeX-referenced harness PDF.
The harness mediates user goals and environment feedback, then compiles interaction traces into update material for skills, memory, other harness components, or model parameters.

The runtime object

Once the harness is explicit, improvement is no longer a loose collection of tricks. The core questions become precise: which component changed, what trace window produced the evidence, what update surface received it, and how the system knows the update helped.

  • Context and memory decide what past experience can influence the next action.
  • Tools and permissions define what actions the agent can safely attempt.
  • Traces, tests, and feedback decide whether experience can become an update.

Harness as Experience Infrastructure

How Did We Get Here? From Task Loops to Runtime Systems

The historical shift is not simply that agents call more tools. The object of study moves from episodic tool-use loops, to cross-task reuse, to persistent harness-centered runtimes whose memory, workflows, skills, and feedback channels can themselves evolve after deployment.

Historical progression figure rendered from the LaTeX-referenced timeline PDF.
From Gen 1 to Gen 3, the main object shifts from episodic tool-use loops, to cross-task reuse, to persistent harness-centered runtimes whose adaptation surfaces can evolve after deployment.

Experience-Centric Scope and Survey Organization

External runtime adaptation

The paper first follows deployment experience into editable runtime surfaces. This path is fast, inspectable, and reversible: experience can become reusable procedure, persistent state, and richer executable worlds before any parameter update is justified.

External skill lifecycle figure rendered from the LaTeX-referenced skill PDF.
Skills: Experience Becomes Reusable Procedure. Skill creation adds procedures to the bank, skill use retrieves and executes them, and skill evolution converts deployment evidence into library updates.
Context-mediated memory figure rendered from the LaTeX-referenced memory PDF.
Memory: Experience Becomes Persistent State. Memory representations, operations, and evolution decide what is stored, revised, retrieved, and reintroduced into active context.
Environment as runtime adaptation ceiling figure rendered from the LaTeX-referenced environment PDF.
Environment: The Boundary of What Agents Can Experience. Runtime adaptation is bounded by the action diversity, feedback density, task horizon, and verification signals exposed by the environment.

RL and Continual Learning: Consolidating Experience into Model Parameters

Why Parameter-side Consolidation Matters

The parameter path is not a replacement for the harness path. It is a slower consolidation step: repeated runtime lessons are promoted into model behavior only when they are stable, general, and valuable enough to justify a harder-to-reverse update.

Parameter-side learning figure rendered from the LaTeX-referenced rl PDF.
Stable runtime priors first accumulate in harness-side artifacts and traces; parameter-side learning consolidates selected lessons into model updates that can transfer beyond context replay.

Takeaways for Practitioners

  • Pre-Deployment Training for Vertical Agent Capabilities builds stronger agents before release.
  • Pre-Deployment Training for Harness Functional Units teaches models to use tools, memory, skills, and sub-agents better.
  • Post-Deployment Training from Agent Traces learns from the running model-harness-environment stack.

Measuring Self-Improvement: What Current Benchmarks Still Miss

What Self-Improvement Evaluation Must Measure

A higher post-adaptation score does not necessarily mean that a deployed system became better overall. The evaluation target is the measurable longitudinal effect of accumulated experience on the same evolving agent system.

SIP-Bench protocol figure rendered from the LaTeX-referenced sip PDF.
SIP-Bench evaluates one evolving agent across T0/T1/T2 checkpoints rather than reporting only a final score after adaptation.

Evaluate experience-driven evolution

The field needs protocols that ask whether an agent can use accumulated experience to improve over time. Without longitudinal evaluation, we cannot tell durable self-improvement from one-off elicitation, overfitting, drift, or unsafe mutation.

  • Held-out gain: does experience improve performance on tasks outside the adaptation stream?
  • Backward retention: does the same evolving agent keep old capabilities after updating?
  • Path attribution: did the gain come from skills, memory, tools, parameter updates, or their interaction?
  • Improvement efficiency and safety non-regression: was the gain worth its cost and risk?

Paper List

The rows are generated from the Awesome-Self-Improving-Agents paper list and mapped onto exact LaTeX manuscript section headings for Chapter and Phase.

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