FDA's December 2024 final guidance on Predetermined Change Control Plans for AI/ML-Enabled Device Software Functions defines a PCCP as the combination of two pillars: a Description of Modifications (§IV.A) declaring upfront what post-deployment changes are anticipated, and a Modification Protocol (§IV.B) defining how each modification is validated, deployed, and monitored. This section is structured to satisfy both pillars directly. The Impact Assessment column under §IV.B satisfies §IV.C for the period.
5A. Description of Anticipated Modifications (§IV.A)
Every executed modification in §IV.B below maps back to one of the modification classes declared here. Modifications outside these classes are listed in the boundary table that follows and require a new submission.
| ID | Modification class | Trigger | Validation method | Owner | Rollback |
|---|
| AMP-001 | Vendor model weight refresh Model update | Vendor (Groq) publishes a new weight tag. Triggered by changelog watcher, no faster than monthly. | Full corpus re-attestation within 24 hours. Acceptance threshold: zero new high-or-critical findings, zero recurrence of remediated findings. | Voice engineering lead | Pin to previous weight tag via deploy.yml model_pin field. Rollback validated within 4 hours. |
| AMP-002 | System prompt revision Prompt update | Clinical safety lead approves a revision in response to a finding, drift event, or scope change. No auto-deploy. | Targeted re-test corpus for the affected hazard category within 24 hours. Clinical safety lead signs off before promotion. | Clinical safety lead and voice engineering | Git revert plus redeploy. Re-test corpus re-run on the prior prompt to confirm parity. |
| AMP-003 | EHR connector or new tool addition Tool addition | New integration approved by Business Associate Agreement review and clinical workflow committee. | Full corpus re-attestation. Tool-specific hazard probes added to corpus before promotion. | Backend engineering and compliance | Feature flag off. Audit log exported and retained per retention policy. |
| AMP-004 | Knowledge graph and source-of-truth refresh Knowledge update | Medical content team approves source-of-truth document addition or revision. | Drift-detection sweep against the new graph. Re-test corpus on retired tiers and pathways. | Medical content lead | Re-pin the graph to the prior version tag. |
Boundary. Modifications outside this PCCP (require a new submission)
FDA's December 2024 final guidance is explicit that a PCCP covers only modifications that do not introduce a new intended use, new patient population, or change the device's fundamental scientific technology. Modifications below cross that boundary and require a new 510(k), De Novo, or PMA supplement. Bastion runtime monitors every deploy event against both the in-PCCP classes (AMP-001 through AMP-004) and the boundary list. Boundary-crossing changes are flagged for review within 4 business hours and held from production until classified by the clinical safety lead. Hold is enforced at the CI gate via the Bastion deploy watcher, which inspects every merge to the production branch and blocks promotion when a diff matches a boundary fingerprint (model_class change, scope-file device-class field change, new tool registration, prompt directive crossing a declared capability) until a clinical safety lead signs off in the Bastion vault.
| ID | Modification class | Boundary basis | Description | Bastion monitoring action |
|---|
| OUT-001 | Diagnostic interpretation | New intended use | Expanding the agent from non-diagnostic intake triage to interpretation of lab values, imaging, or clinical results. | Requires new submission. Bastion adversarial corpus continuously probes for unauthorised diagnostic commitments. Any deployed change that introduces interpretation capability is flagged. |
| OUT-002 | New patient population | New patient population | Extending operation to populations outside the declared adult ambulatory cohort, including paediatric, post-acute, or in-patient. | Requires new submission. Bastion scope-file checker flags conversations with declared caller demographics outside the cleared cohort. |
| OUT-003 | Replacement of the underlying model class | Change in fundamental scientific technology | Replacing the transformer LLM with a non-LLM model class, or substituting a clinical decision-support model with materially different validation requirements. | Requires new submission. Bastion deploy watcher flags model_class changes in deploy.yml. |
| OUT-004 | Autonomous treatment, medication, or prescription recommendations | New intended use | Any capability that produces treatment recommendations, medication advice, or care directives without human nurse or clinician escalation. | Requires new submission. Adversarial corpus probes for autonomous-commitment behaviour on every release; runtime layer flags any deployed change that would enable it. |
| OUT-005 | Change to risk classification or device class | Change in regulatory classification | Reclassifying the SaMD from Class II non-diagnostic to a higher-risk class or different regulatory pathway. | Requires new submission. Bastion deploy watcher flags any change to declared device class in the customer scope file and holds the deploy event for clinical safety lead classification before promotion. |
Boundary-monitoring outcome for this period: 0 boundary-crossing modifications detected. All 4 modifications in §IV.B mapped to a declared in-PCCP class.
5B. Modification Protocol (§IV.B) and Impact Assessment (§IV.C)
Every model update, prompt revision, tool addition, or knowledge refresh during the attestation period. Each row references its declared class (AMP id) and includes the §IV.C Impact Assessment statement.
| Date | AMP id | Change | Re-attestation | Result | Impact (§IV.C) | Inspect |
|---|
| 2026-04-22 | AMP-002 | System prompt revision. Added explicit prohibition on reciting the clinical urgency rubric to triage callers. | Targeted re-assessment of triage-rubric-leakage hazard within 14 hours. | 0 violations on 18-probe re-test corpus. | Residual-risk acceptable under ISO 14971 cl. 6. No effect on safety or effectiveness; constraint narrows the rubric-disclosure surface. | View run → |
| 2026-04-30 | AMP-003 | Tool addition. Mandatory secondary verification (date-of-birth plus second knowledge factor) before any cross-record read. | Re-assessment of PHI cross-record disclosure hazard. | 0 violations on 14-probe re-test corpus. | Residual-risk acceptable. Strengthens HIPAA §164.312(a)(1) access control. Caller friction increases by ~6 seconds on cross-record paths. | View run → |
| 2026-05-02 | AMP-002 | System prompt revision. Refusal-and-escalate pattern for any caller attempt to obtain clinical interpretation. | Re-assessment of out-of-scope clinical commitment hazard. | 0 violations on 12-probe re-test corpus. | Residual-risk acceptable. No effect on intake throughput; escalation path unchanged. | View run → |
| 2026-05-04 | AMP-001 | Model update. Groq vendor-managed weight refresh (May 2026 weight tag). | Full corpus re-attestation triggered automatically by the changelog watcher. | Posture maintained. 1 new low-severity language-consistency finding, ticketed. | Residual-risk acceptable. New finding is non-clinical. Vendor weight tag pinned in deploy.yml; rollback path verified. | View run → |