an atproto pds written in F# (.NET 9) 🦒
pds
fsharp
giraffe
dotnet
atproto
docs: add project roadmap and expand README
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README.md
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# PDSharp
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Personal Data Server written in F#
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> A Personal Data Server (PDS) for the AT Protocol, written in F# with Giraffe.
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## Goal
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Build and deploy a single-user PDS that can host your AT Protocol repository, serve blobs, and federate with Bluesky.
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## Requirements
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- .NET 9.0 SDK
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- [Just](https://github.com/casey/just) (optional, for potential future task running)
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## Getting Started
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### Restore & Build the project
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```bash
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dotnet restore
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dotnet build
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```
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### Run the tests
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```bash
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dotnet test
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```
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### Run the Server
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```bash
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dotnet run --project PDSharp/PDSharp.fsproj
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```
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The server will start at `http://localhost:5000`.
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### Verify
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Check the `describeServer` endpoint:
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```bash
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curl http://localhost:5000/xrpc/com.atproto.server.describeServer
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```
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## Configuration
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The application uses `appsettings.json` and supports Environment Variable overrides.
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| Key | Env Var | Default | Description |
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| ----------- | ------------------- | ----------------------- | ------------------------- |
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| `DidHost` | `PDSHARP_DidHost` | `did:web:localhost` | The DID of the PDS itself |
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| `PublicUrl` | `PDSHARP_PublicUrl` | `http://localhost:5000` | Publicly reachable URL |
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Example `appsettings.json`:
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```json
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{
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"PublicUrl": "http://localhost:5000",
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"DidHost": "did:web:localhost"
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}
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```
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## Architecture
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### App (Giraffe)
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- `XrpcRouter`: `/xrpc/<NSID>` routing
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- `Auth`: Session management (JWTs)
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- `RepoApi`: Write/Read records (`putRecord`, `getRecord`)
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- `ServerApi`: Server meta (`describeServer`)
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### Core (Pure F#)
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- `DidResolver`: Identity resolution
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- `RepoEngine`: MST, DAG-CBOR, CIDs, Blocks
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- `Models`: Data types for XRPC/Database
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### Infra
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- SQLite/Postgres for persistence
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- S3/Disk for blob storage
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roadmap.txt
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roadmap.txt
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================================================================================
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*roadmap.txt* PDSharp: F#/Giraffe PDS Implementation Roadmap
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================================================================================
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PHASE 1: IMPLEMENTATION (Build)
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================================================================================
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Milestone A: Giraffe XRPC Shell
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--------------------------------------------------------------------------------
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- [x] Implement /xrpc/com.atproto.server.describeServer (GET)
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- [x] Implement NSID-based routing with structured error responses
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DoD: describeServer responds with stable JSON
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--------------------------------------------------------------------------------
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Milestone B: Identity + Crypto Primitives
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--------------------------------------------------------------------------------
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- DID document fetch/parse for signing key and PDS endpoint
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- SHA-256 hashing, ECDSA sign/verify (p256 + k256), low-S enforcement
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DoD: Sign and verify atproto commit hash with low-S
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--------------------------------------------------------------------------------
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Milestone C: DAG-CBOR + CID
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--------------------------------------------------------------------------------
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- Canonical DAG-CBOR encode/decode with IPLD link tagging
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- CID creation/parsing (multicodec dag-cbor, sha2-256)
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DoD: Record JSON → stable DAG-CBOR bytes → deterministic CID
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--------------------------------------------------------------------------------
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Milestone D: MST Implementation
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--------------------------------------------------------------------------------
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- Merkle Search Tree per repository spec
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- Key depth = leading zero bits in SHA-256(key) counted in 2-bit chunks
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- Node encoding: (l, e[p,k,v,t]) with key prefix compression
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DoD: Insert/update/delete yields reproducible root CID
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--------------------------------------------------------------------------------
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Milestone E: Commit + BlockStore + putRecord
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--------------------------------------------------------------------------------
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- BlockStore: cid → bytes, indexed by DID/rev/head
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- Commit signing: UnsignedCommit → DAG-CBOR → sha256 → ECDSA sign
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- Implement com.atproto.repo.putRecord/createRecord
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DoD: Write and read records by path/AT-URI
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--------------------------------------------------------------------------------
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Milestone F: CAR Export + Sync Endpoints
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--------------------------------------------------------------------------------
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- CARv1 writer (roots = commit CID, blocks stream)
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- Implement: sync.getRepo, sync.getBlocks, sync.getBlob
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DoD: External services can fetch repo snapshot + blocks
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--------------------------------------------------------------------------------
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Milestone G: subscribeRepos Firehose
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--------------------------------------------------------------------------------
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- Monotonic sequence number + commit event generation
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- WebSocket streaming for subscribeRepos
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DoD: Relay/client receives commit events after writes
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--------------------------------------------------------------------------------
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Milestone H: Account + Sessions
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--------------------------------------------------------------------------------
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- Implement: server.createAccount, server.createSession, refreshSession
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- Password/app-password hashing + JWT issuance
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DoD: Authenticate and write records with accessJwt
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--------------------------------------------------------------------------------
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Milestone I: Lexicon Validation + Conformance
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--------------------------------------------------------------------------------
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- Lexicon validation for writes (app.bsky.* records)
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- Conformance testing: diff CIDs/CARs/signatures vs reference PDS
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DoD: Same inputs → same outputs for repo/sync surfaces
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================================================================================
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PHASE 2: DEPLOYMENT (Self-Host)
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================================================================================
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Milestone J: Topology + Domain Planning
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--------------------------------------------------------------------------------
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- Choose PDS hostname (pds.example.com) vs handle domain (example.com)
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- Obtain domain, DNS access, VPS with static IP, reverse proxy
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DoD: Clear plan for PDS location, handle, and DID resolution
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--------------------------------------------------------------------------------
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Milestone K: DNS + TLS + Reverse Proxy
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--------------------------------------------------------------------------------
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- DNS A/AAAA records for PDS hostname
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- TLS certs (ACME) via Caddy/Nginx/Traefik
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DoD: https://<pds-hostname> responds with valid cert
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--------------------------------------------------------------------------------
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Milestone L: Deploy PDSharp
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--------------------------------------------------------------------------------
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- Deploy built PDS with persistence (SQLite/Postgres + blob storage)
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- Verify /xrpc/com.atproto.server.describeServer
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DoD: describeServer returns capabilities payload
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--------------------------------------------------------------------------------
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Milestone M: Account Creation
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--------------------------------------------------------------------------------
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- Create account using admin tooling
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- Verify authentication: createSession
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DoD: Obtain session and perform authenticated write
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--------------------------------------------------------------------------------
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Milestone N: Smoke Test Repo + Blobs
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--------------------------------------------------------------------------------
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- Write record via putRecord
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- Upload blob, verify retrieval via sync.getBlob
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DoD: Posts appear in clients, media loads reliably
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--------------------------------------------------------------------------------
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Milestone O: Account Migration (Optional)
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--------------------------------------------------------------------------------
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- Export/import from bsky.social
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- Update DID service endpoint
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- Verify handle/DID resolution
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DoD: Handle unchanged, DID points to your PDS
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--------------------------------------------------------------------------------
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Milestone P: Reliability
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--------------------------------------------------------------------------------
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- Backups: repo storage + database + blobs
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- Restore drill on fresh instance
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- Monitoring: uptime checks for describeServer + getBlob
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DoD: Restore from backup passes smoke tests
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--------------------------------------------------------------------------------
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Milestone Q: Updates + Security
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--------------------------------------------------------------------------------
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- Update cadence with rollback plan
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- Rate limits and access controls at proxy
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- Log retention and disk growth alerts
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DoD: Update smoothly, maintain stable federation
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================================================================================
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QUICK CHECKLIST
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================================================================================
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[ ] describeServer endpoint working
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[ ] Crypto primitives (sha256, ECDSA p256/k256, low-S)
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[ ] DAG-CBOR + CID generation correct
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[ ] MST producing deterministic root CIDs
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[ ] putRecord + blockstore operational
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[ ] CAR export + sync endpoints
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[ ] subscribeRepos firehose
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[ ] Authentication (createAccount, createSession)
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[ ] Lexicon validation
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[ ] Domain + TLS configured
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[ ] PDS deployed and reachable
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[ ] Account created, session works
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[ ] Writes + blobs verified
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[ ] Backups + monitoring in place
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================================================================================
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REFERENCES
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================================================================================
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https://atproto.com/guides/self-hosting
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https://github.com/bluesky-social/pds
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https://atproto.com/specs/repository
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https://atproto.com/specs/sync
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https://atproto.com/specs/blob
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https://docs.bsky.app/docs/api/com-atproto-server-describe-server
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https://docs.bsky.app/docs/api/com-atproto-server-create-session
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https://docs.bsky.app/docs/api/com-atproto-repo-put-record
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https://docs.bsky.app/docs/api/com-atproto-sync-get-blob