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Agent sandbox assurance

Sandbox image supply-chain review

Control the provenance and contents of sandbox images

A base image or build process is changing. The decision is how to control the provenance and contents of sandbox images. The work begins with your actual workflow and looks for the evidence that separates intended behaviour from a consequential exception. It is particularly relevant to platform supply-chain and security engineers. A useful outcome is an explicit account of what was examined, what remains uncertain, and which decision the evidence can support.

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The runtime isolation relationship

  1. Starting evidenceImage manifests

    Establish the basis for build recipe.

  2. Decision boundaryImage identity

    Connect deployed digest to provenance evidence.

  3. Decision artefactImage supply-chain map

    Retain the scoped finding and its unresolved dependencies.

Proposed working model. Untested surfaces remain outside the conclusion.

Decision

Frame the decision around build recipe

Questions and the evidence they need

Criterion / evidenceBuild recipe
Inspect image manifests for the relevant constraint or observation.
Criterion / evidenceImage identity
Inspect build recipes for the relevant constraint or observation.
Criterion / evidenceUpdate approval
Inspect dependency inventories for the relevant constraint or observation.
Read each criterion against the available evidence before deciding that additional work is needed.

The decision is how to control the provenance and contents of sandbox images. This is relevant to platform supply-chain and security engineers when a base image or build process is changing. Name the affected workflow, the consequence of a wrong decision, and the owner who can act on the result. The initial discussion should establish which evidence is already available and which uncertainty is material enough to investigate.

The specific failure hypothesis is that a mutable image tag resolves to different executable content between reviewed and deployed runs. It remains a hypothesis until examined in the deployment. Existing internal tests or operating records may already resolve it; identify the uncovered question before commissioning additional work.

Mechanism

The deployed image must trace back to reviewed inputs

Relationships within runtime isolation

Source or conditionBuild recipe
Identify dependency sources and assembly steps.
Crossing or choiceImage identity
Connect deployed digest to provenance evidence.
Consequence or decisionUpdate approval
Preserve review and rollback decisions across revisions.
Compare effective controls with harmless test observations. Each relationship needs evidence in the actual scope.

What this specialty examines

Image review should identify immutable deployed content and its build lineage. Record base images, packages, build steps and approval inputs. A mutable tag describes a selection mechanism, not necessarily the exact executable artefact examined during review.

The review should trace build inputs to deployed image identity and inspect update, approval and rollback controls. Identify the normal route, relevant exceptions and the authoritative record of the outcome. Inspect the relevant business-system record, enforcement event or process evidence alongside any reported status. Keep incomplete cases visible, with an explanation of what their absence prevents the owner from concluding.

The tradeoff to make explicit

For this decision, frequent updates address known issues while every change needs traceable validation. Compare the available design or operating choices against the same intended outcome. If one option removes a required control or changes the task boundary, describe that difference before treating its apparent simplicity, speed or lower effort as an improvement. The decision should expose the tradeoff instead of burying it in an aggregate score.

Preparation

Connect the working inputs to the boundary being examined

Evidence packet for build recipe

Illustrative working format

BasisImage manifests
Connect the deployed artefact to its inputs, approval, and verifiable revision.
ContextBuild recipes
Connect the deployed artefact to its inputs, approval, and verifiable revision.
ObservationDependency inventories
Name the custodian and the conditions requiring a refreshed version.
DependencySigning or provenance records
Connect the deployed artefact to its inputs, approval, and verifiable revision.
Illustrative preparation record. Availability, revision, and handling need confirmation.

Start with image manifests, build recipes, dependency inventories and signing or provenance records. Identify the owner, revision and operating context of each source. Sanitised examples may support initial design, but differences from actual conditions should remain explicit. Where direct access is unsuitable, a customer-controlled evidence or execution route may be considered, with agreed handling and retention.

The scope also needs the runtime owner, agreed expectations for a representative boundary test, and the authority to inspect the relevant boundary. Specify what evidence would distinguish the failure in which a mutable image tag resolves to different executable content between reviewed and deployed runs from acceptable behaviour. If stakeholders disagree about intended behaviour, resolve the interpretation before classifying the observed difference as a defect.

How the work proceeds

Carry build recipe through to an accountable finding

From the scoped material to a decision record

  1. Establish conditionsImage manifests

    Declare the permitted environment and resources.

  2. Examine the relationshipImage identity

    Apply the scoped check to update approval.

  3. Retain the findingImage supply-chain map

    Record the evidence, open dependencies, and the owner’s next decision.

Proposed sequence; resolve interpretation or access gaps before relying on the next step.

Prepare the runtime boundary and fixtures

Use image manifests, build recipes, dependency inventories and signing or provenance records to identify the exact runtime and boundary claimed by platform supply-chain and security engineers. Mark permitted resources and protected resources in a controlled fixture, including shared services where they are relevant. Define observable success, denial and incomplete setup before execution. The preparation output is a boundary map and fixture manifest that lets reviewers distinguish effective isolation from a test that never reached its target.

Exercise and inspect the boundary

Trace how updates reach workers and how rollback selects a known image. Evaluate whether provenance and signatures are checked where expected. Dependency inventories support investigation, but their presence alone does not establish that every dependency is acceptable.

Choose containment or configuration changes

Translate the observations into an image supply-chain map and evidence request for unverified build dependencies. Locate each issue in the worker, shared service, policy rollout or cleanup path rather than attributing every symptom to the sandbox as a whole. Decide which configuration change, narrower resource exposure or specialist investigation is warranted. Retest the affected boundary and inspect residual state before treating the changed environment as equivalent to the intended design.

Indicative artefact

Make the image supply-chain map usable by its owner

Image supply-chain map

Illustrative working format

Annotated fieldImage supply-chain map
Identify the assessed workflow, revision, and decision boundary.
Annotated fieldEvidence request for unverified build dependencies
Name the missing evidence, responsible owner, and condition for revisiting the decision.
Annotated fieldImage identity evidence
Link observations and counterevidence to the case, configuration, and conclusion limit.
Illustrative artefact structure, not a completed engagement or an observed result.

A useful decision artefact is an image supply-chain map and evidence request for unverified build dependencies. Supporting material may include selected cases, configuration or process records, evidence references, a disagreement log and prioritised actions. Retain the case selection rationale and material disagreements alongside the result; otherwise the result may be mistaken for complete coverage.

Illustrative scenario

Examine update approval through a constructed exception

A constructed case and its decision paths

Illustrative scenario

  1. SituationBuild recipe

    A rebuilt image uses an unreviewed dependency under the same friendly tag.

  2. Question to examineImage identity

    Compare deployed image digests with the reviewed build inputs.

  3. Conditional next actionUpdate approval

    Require provenance for the actual revision rather than trusting its tag.

Fictional example. No executed test, customer engagement, or measured outcome is implied.

Consider a fictional situation: a reviewed coding image is referenced by a mutable tag and later includes an unreviewed helper package. The scenario is illustrative, with no client engagement, executed test or measured improvement implied.

For the changed helper package, compare the reviewed digest with the deployed digest. The immediate question is whether change control detected and authorised the difference. Retesting should focus on the behaviour and privileges that the new content can affect.

Scope and next action

Keep the conclusion within the authorised runtime boundary

Confirm fit before the next commitment

Included boundaryBuild recipe
This review is limited to the authorised runtime boundary.
PrerequisiteImage manifests
The relevant owner must confirm access and the intended operating conditions.
Claim limitImage supply-chain map
Untested surfaces remain outside the conclusion.
Bring the triggering change and existing evidence; resolve the dependency that could alter the decision.

Testing is confined to explicitly authorised environments and non-destructive cases. A bounded assessment cannot establish that escape or cross-boundary access is impossible. Any engagement depends on an agreed scope, qualified team, authorised access and confirmed availability. Bring the affected workflow, its current configuration or process, the triggering change and the evidence already available. The immediate scope question is prompted by the situation in which a base image or build process is changing; confirm which missing observation would change the owner’s next action.

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A little more clarity

Questions to consider.

Start with the questions that shape a better decision.

Is an image name or tag enough to identify what was tested?

No. Mutable names can resolve to different content over time. Retain the deployed image identity and build provenance so reviewed and executed artefacts can be compared precisely.

Which build records identify the deployed image?

Start with image manifests, build recipes, dependency inventories and signing or provenance records. Record their revision, owner and relationship to the intended workflow. Missing context should be identified before interpreting outcomes; a sanitised fixture is useful only when its relevant differences from the operating case are understood.

How should mutable image updates be reviewed?

Trace build inputs to deployed image identity and inspect update, approval and rollback controls. Retain effective runtime configuration and observations from the relevant boundary. Distinguish an enforced denial from failed setup or an operation that never reached the resource. Use controlled markers and preserve residual-state evidence.

What should an image provenance map contain?

The proposed output is an image supply-chain map and evidence request for unverified build dependencies. Include the selected conditions, supporting observations, unresolved differences and next decision. A reviewer should be able to follow each important conclusion back to its evidence and understand the limits without depending on an undocumented explanation from the author.

When should an image change trigger retesting?

Retest when image contents or configuration changes affect relevant behaviour, privileges or controls. Use the immutable image identity to determine what changed rather than assuming a stable tag means stable content.

What if existing evidence already answers the question?

Review its scope, provenance and configuration before proposing new work. Existing work from platform supply-chain and security engineers may already be sufficient. In that case, capture the decision, unresolved limitations and the change that would require another review. Additional assessment should address a real gap.

What would make the findings inconclusive?

Missing image manifests, build recipes, dependency inventories and signing or provenance records can prevent a reliable interpretation, depending on the case. Record the specific missing observation and its implication. The owner can supply evidence, narrow the claim or defer the dependent decision; an incomplete case should not silently be counted as a pass.

Start with the decision you need to make.

Tell us about the agent workflow you want reviewed, and where you need greater clarity. Scope and availability are confirmed together.

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Connected disciplines

Runtime-policy validation

Confirm that runtime restrictions are enforced in the deployed configuration. The review connects policy files, launch parameters, enforcement logs and representative workload fixtures to a bounded review of execution boundaries, giving the runtime owner a clearer basis for the next action.

Snapshot and rollback testing

Determine what a snapshot can restore after an agent failure. The review connects snapshot scope, external tool state, storage dependencies and recovery procedures to a bounded review of execution boundaries, giving the runtime owner a clearer basis for the next action.

Auditability assessment

Make sandbox activity reconstructable for operational review. The review connects event schemas, timestamp sources, retention rules and correlation identifiers to a bounded review of execution boundaries, giving the runtime owner a clearer basis for the next action.