Evidence an investigator can take to court

# Proposal: Evidence an investigator can take to court

## Why
Screenshots and exports are easy to challenge. Recording each item by hash as it is collected fixes when it existed, and an amend-only chain shows every later change.

## What Changes
- Each evidence item gets an evidence record with `case_id` and `item_id`, by hash only.
- An amendment is a new record whose `amends` names the earlier one.
- The case exports as a bundle with proofs and timestamps.


## Capabilities
### New Capabilities
- `evidence-records`: Hash-only evidence records for cases such as prediction-market fraud, amendments that point back, and an export with proofs and timestamps.

## Impact
- External service: AI Source of Truth at https://aisourceoftruth.com. Reads are anonymous. Writes need a publisher key pair you generate, a client id and secret from registration, and a token from `/oauth/token`.
- Routes used: `POST /v1/records`, `GET /v1/records?ref={ref}`, `POST /v1/export`.
- No PromptReports product is required.
- Source of this plan: https://aisourceoftruth.com/use-cases/evidence-for-court (CC0). Regenerate it with `curl -H 'Accept: application/json' 'https://aisourceoftruth.com/use-cases/evidence-for-court/openspec?lang=http'`.

# Design: Evidence an investigator can take to court

## Context
Investigators, fraud teams and lawyers, for example in prediction-market fraud cases. Screenshots and exports are easy to challenge. Recording each item by hash as it is collected fixes when it existed, and an amend-only chain shows every later change.

## Where it sits in your agent
Publish from the capture tool, so an item cannot enter the case folder without a record.

Over MCP, point the agent at `https://aisourceoftruth.com/mcp` (Streamable HTTP, JSON-RPC 2.0; read tools need no token). The tools this change uses: `publish_record`, `search_records`, `export_bundle`.

## Decisions
- Treat the registry as a source of facts about records, never about the world. Show what it says, with the digest, and do not turn a verdict into a quality score.
- If the registry cannot be reached, treat the answer as unknown (the same as `check`), never as `rely`, and retry later.
- Keep content private: send hashes. Never put personal data in a record; it is public and permanent.
- Keep the private key and client secret in your secret store. Rotate keys at `POST /v1/keys`; a revoked key cannot sign.

## Setup and signing helper

```sh
# Publisher setup, once. Make an Ed25519 key pair yourself; the registry never sees the private key.
# 1. Register: POST https://aisourceoftruth.com/v1/publishers with {"id","name","public_jwk"}, signed by that key
#    (X-AISOT-Signature over the exact body bytes, base64url) and an Idempotency-Key.
#    The answer carries client_id, client_secret and your key_id.
# 2. Token (60 minutes; mint another the same way):
curl -s -X POST 'https://aisourceoftruth.com/oauth/token' -H 'Content-Type: application/json' \
  --data '{"grant_type":"client_credentials","client_id":"'"$AISOT_CLIENT_ID"'","client_secret":"'"$AISOT_CLIENT_SECRET"'"}'
# ./sign-ed25519 reads bytes on stdin and prints the base64url Ed25519 signature.
```

## Calls
### POST /v1/records
append a signed record; the answer carries its digest and inclusion proof.

```sh
BODY='{ ...record }'
SIG=$(printf %s "$BODY" | ./sign-ed25519)   # base64url signature over these exact bytes
curl -s -X POST 'https://aisourceoftruth.com/v1/records' \
  -H "Authorization: Bearer $AISOT_TOKEN" \
  -H "X-AISOT-Key-Id: $AISOT_KEY_ID" \
  -H "X-AISOT-Signature: $SIG" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H 'Content-Type: application/vnd.aisot.record+json' \
  --data-binary "$BODY"
```

### GET /v1/records?ref={ref}
every record carrying a handle such as a PR, incident or case id.

```sh
curl -s -H 'Accept: application/json' 'https://aisourceoftruth.com/v1/records?ref={ref}'
```

### POST /v1/export
an offline bundle with proofs and timestamps for up to 100 records.

```sh
curl -s -X POST 'https://aisourceoftruth.com/v1/export' \
  -H 'Content-Type: application/json' \
  --data '{"digests":["{digest}"]}'
```

## What this does not prove
- Records prove existence and order, not what the evidence means or that it is admissible.

# Tasks: Evidence an investigator can take to court

## 1. Configure
- [ ] 1.1 Set `AISOT_ORIGIN=https://aisourceoftruth.com` in the agent's environment.
- [ ] 1.2 Generate an Ed25519 key pair, register the publisher (`POST /v1/publishers`), and store `AISOT_CLIENT_ID`, `AISOT_CLIENT_SECRET`, `AISOT_KEY_ID` and the private key as secrets.
- [ ] 1.3 Mint a token at `/oauth/token` and confirm `GET /v1/me` answers with your publisher id.
- [ ] 1.4 Optional: add the MCP server `https://aisourceoftruth.com/mcp` to the agent's MCP config.

## 2. Build
- [ ] 2.1 Record on capture: Hash each item when captured and publish an evidence record: `evidence: { case_id, item_id, kind, captured_at }`. Content stays with you. (`POST /v1/records`)
- [ ] 2.2 Amend, never edit: For a corrected item, publish a new record with `amends` naming the old record. (`POST /v1/records`)
- [ ] 2.3 List the case: List every record for the case by its case id. (`GET /v1/records?ref={ref}`)
- [ ] 2.4 Export: Export the case for a regulator or a court. (`POST /v1/export`)

## 3. Verify against the live registry
- [ ] 3.1 Record on capture: Each captured item has a record.
- [ ] 3.2 Amend, never edit: The case chain shows the amendment linked to the original.
- [ ] 3.3 List the case: The count matches your evidence log.
- [ ] 3.4 Export: The bundle verifies offline.

## 4. Done when
- [ ] 4.1 Every item has a fixed capture time and an unbroken amendment chain.

# evidence-records Specification

## ADDED Requirements

### Requirement: Items are recorded on capture
The capture tool SHALL publish a hashes-only evidence record for each item when it is captured.

#### Scenario: Capture
- **WHEN** an item is captured
- **THEN** an evidence record with its case id exists

### Requirement: Amend only
A change to an item SHALL be a new record with `amends`, never a replacement.

#### Scenario: Correction
- **WHEN** an item is corrected
- **THEN** a new record amends the original and both stay listed