For · Counsel vertical
HMAC · SHA-256 · CHAIN

Outside-counsel AI diligence

Walk any decision back to the model version that produced it.HMAC-signed records. SHA-256 PDFs. One ledger your counsel already has the tooling to investigate.

The discovery scramble doesn’t have to be exhaustive; it has to be defensible. Plumbline writes every model decision onto a per-workspace HMAC-SHA-256 chain so when counsel opens the record six months from now, what they re-derive is what the model said — not a reconstruction joined from telemetry after the fact. Per-workspace HMAC anchored to the buyer’s KMS, SHA-256 footers on every exported PDF, hash-chained run history across model versions, retention windows negotiated in the DPA, and a tamper-evident audit PDF opposing counsel can re-derive from the public surface.

Reserve a counsel / vendor-diligence pilotSee Enterprise pricingRead the chain walk-through →

§01 · Counsel diligence

What counsel asks post-incident — and where Plumbline lives in the answer.

Counsel’s diligence questions are almost always the same six. Every row below is a real counsel-shaped question and the Plumbline artifact the ledger already produces on the way through — no after-the-fact paste-up, no engineering handoff when opposing counsel wants to re-verify.

  1. Vendor diligence · re-verifiability

    Q. How do I independently re-verify any record six months from now, without phoning the vendor?

    Plumbline artifact · HMAC · KMS-ANCHORED

    Per-workspace HMAC-SHA-256 on canonical-JSON, anchored to the buyer’s KMS. The public /verify page runs pure computation — no oracle, no platform call. Counsel re-derives the signature offline with the canonicalization script.

  2. Discovery production · tamper-evidence

    Q. How do I prove the PDFs I hand opposing counsel haven’t been altered since they were issued?

    Plumbline artifact · SHA-256 · COVER + HEADER

    SHA-256 of the canonical-JSON payload burns into the cover footer; X-PDF-SHA256 response header carries the SHA-256 of the PDF bytes. One covers the contents, one covers the file. Both are independently verifiable with sha256sum.

  3. Model lifecycle · chain continuity

    Q. If the vendor swapped model versions mid-quarter, can I walk back old decisions to the exact version that produced them?

    Plumbline artifact · CHAIN · MODEL-VERSIONED

    The chain is over the canonical-JSON record view — input digest, scorer id + parameters, model id + version. Each row carries prev_hash; the model-version change itself is a row. The walk-back reconstructs what the model said on the day, not what it says now.

  4. Retention · litigation hold

    Q. How long will my record set survive, and can I negotiate a longer window for a litigation hold?

    Plumbline artifact · RETENTION · DPA-NEGOTIATED

    Retention is configured at write time from the same tier-catalog.ts source /security and /pricing read — the buyer cannot drift from it. Enterprise tier carries customRetention: a buyer-specific window negotiated into the DPA.

  5. Tamper-evidence · access roles

    Q. Has anyone touched this record since it was captured? Can I tell who read it?

    Plumbline artifact · TAMPER · VISIBLE-AT-FETCH

    HMAC-SHA-256 chain breaks visibly at the next record the moment the canonical-JSON changes; detection runs at fetch. Read events carry role + key fingerprint, and the sub-processor matrix ships under NDA on request.

  6. Discovery production · audit bundle

    Q. What do I hand opposing counsel when production is due — and how do they verify it without our team?

    Plumbline artifact · AUDIT PDF · /verify

    A tamper-evident audit PDF (model card + record hash + signature chain) plus the canonical-JSON bundle and the verification manifest. Opposing counsel re-derives the chain hash against /verify; no engineering handoff, no vendor approval loop.

§02 · The incident walk-back

A 30-day-old procurement decision, opened for re-review.What the record carries — and what counsel walks back.

  1. 1.What decision did the model surface on the day? The procurement pick (tier-2 shortlist) and the four evaluator scores sit on the same row as the model id + version and the timestamps at capture.
  2. 2.Which exact model version produced this score — and could counsel re-derive it? The row carries model id + version and the chain’s prev_hash. The walk-back jumps to the model-version change row and reads the version that was active on the day, not the version active now.
  3. 3.Has anyone edited, redacted, or touched this record since capture? The HMAC-SHA-256 chain breaks visibly at the next record on any change; detection runs at fetch, not at audit time. Read events carry role + key fingerprint.
  4. 4.How long will this record set survive the matter? Retention is configured at write time from tier-catalog.ts — the same source /security reads. Enterprise buyers can negotiate a buyer-specific window into the DPA; the entitlement surfaces as features.customRetention.
  5. 5.Can opposing counsel verify the bundle without our team? Yes. The tamper-evident audit PDF carries a SHA-256 cover footer and the matching X-PDF-SHA256 response header. Verification runs against the public /verify page; no vendor round-trip required.
  6. 6.What does counsel put on the production server when discovery is due? One tamper-evident audit PDF — model card, record hash, signature chain — plus the canonical-JSON bundle and the verification manifest. Counsel reads the same bundle, once.

§03 · Cross-links

Read next, by counsel intent.

Healthcare siblingHIPAA-era OCR / HHS framing for clinical decision support — useful when the same outside-counsel team is advising on the clinical side of the matter.FinServ siblingSR 11-7 model-risk framing and ECOA disparate-impact posture — adjacent for counsel working both sides of a credit / lending litigation.Insurance siblingNAIC SR 12-9 validation framing for claims-adjacent AI — useful when the same outside-counsel team is covering the property-and-casualty side.Pharma sibling21 CFR Part 11 / ALCOA+ / GMLP framing for FDA-regulated clinical-AI and pharmacovigilance work — for the same counsel team advising on a SaMD or GxP matter.Enterprise pricingPer-workspace HMAC key, BAA / DPA, custom retention, region-pinning — the Enterprise tier carries the counsel-shaped evidence package.Chain walk-throughSDK → signed record → drift ledger → signed export. One chain, five stages — the structural walk for the matter handbook.Inspect a signed evidence recordA live signed record on the public surface — open it, hash it, verify the chain position yourself before production.Verify a signed receiptPublic verification of any record’s chain position — pure computation, no oracle. Opposing counsel re-derives, your team hands off once.Security postureTLS 1.3, AES-256 at rest, HMAC-SHA-256 per workspace, RBAC, tier-aware retention, residency, SOC 2 / HIPAA / GDPR readiness — what the InfoSec reviewer hands off to counsel.Audit-export scopeWhat the tamper-evident audit PDF contains and what it does not — the same artifact opposing counsel walks back from /verify.Compare against compliance theaterStructural comparison on evidence capture, tamper-evidence, replay, signing anchors, and verification path. The dimension the matter actually hinges on.
§04 · Talk to us
Two paths in

Reserve a counsel / vendor-diligence pilot, or send us your discovery timeline.

Running a vendor-diligence review on a model purchase and want the diligence walk-through? Drop your email and the counsel scoping checklist lands in your inbox before any contract is drawn up. Have an active matter on the desk? Send us the discovery timeline and we’ll reply with the evidence bundle and a short re-derivability offer.

PLU-008 · Counsel vertical
Vertical pilot
Reserve a counsel / vendor-diligence Evidence Pilot intake
Each counsel pilot ships with a per-workspace HMAC anchored to the buyer’s KMS, a SHA-256 footer on every exported PDF, a hash-chained run history that survives model version changes, a retention window negotiated into the DPA, and a tamper-evident audit PDF you can re-derive from the public /verify page. Drop your email and we’ll send the vendor-diligence scoping checklist before a contract is drawn up.

We'll never share your email. No marketing blast — only the next-step note when a slot opens. If you already have a litigation hold or a model audit on the calendar, mention the date on the call.

Enterprise intake
DPA · litigation hold
Compliance needs

Pick every shape your procurement team will ask about.

§06 · Pricing

Ready to see this on your models?

Start with the $1,000 Evidence Pilot: one workflow, one model, and 30 days ending in a replayable evidence package. Plumbline captures forward from the moment you connect, and the full pilot fee is credited toward Regulated Team.

View pricingRequest a 30-min demoor contact us