diff --git a/AGENTS.md b/AGENTS.md
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--- /dev/null
+++ b/AGENTS.md
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+# PROJECT KNOWLEDGE BASE
+
+**Generated:** 2026-02-12
+**Commit:** 661961a5
+**Branch:** main
+
+## OVERVIEW
+
+Official Go SDK for Stellar blockchain. Provides transaction building (`txnbuild`), API clients (`horizonclient`, `rpcclient`), ledger ingestion (`ingest`), and XDR type definitions. Previously a monorepo—services moved to separate repos (Oct 2025).
+
+## STRUCTURE
+
+```
+go-stellar-sdk/
+├── txnbuild/           # Transaction building API (83 Go files) - START HERE for tx construction
+├── clients/            # Network clients
+│   ├── horizonclient/  # Horizon REST API client (primary)
+│   ├── rpcclient/      # Stellar RPC client
+│   ├── stellarcore/    # Direct stellar-core client
+│   └── stellartoml/    # stellar.toml parser
+├── ingest/             # Ledger data ingestion library
+│   └── ledgerbackend/  # Captive Core, RPC backend, buffered storage
+├── xdr/                # XDR types (MOSTLY GENERATED - see xdr/AGENTS.md)
+├── support/            # Internal utilities (db, http, config, errors, logging)
+├── historyarchive/     # History archive access
+├── protocols/          # Protocol response types (horizon, rpc, stellarcore)
+├── processors/         # ETL-style data processors
+├── strkey/             # Stellar key encoding (G*, S*, M*, P*, C* addresses)
+├── keypair/            # Cryptographic key pair operations
+├── tools/              # Standalone CLI utilities (not library code)
+└── exp/                # DEPRECATED experimental packages
+```
+
+## WHERE TO LOOK
+
+| Task | Location | Notes |
+|------|----------|-------|
+| Build transactions | `txnbuild/` | Start with `NewTransaction()` |
+| Submit to Horizon | `clients/horizonclient/` | Use with txnbuild |
+| Submit to RPC | `clients/rpcclient/` | Soroban smart contracts |
+| Parse ledger data | `ingest/` | LedgerTransactionReader, CheckpointChangeReader |
+| Run Captive Core | `ingest/ledgerbackend/` | CaptiveCoreConfig |
+| XDR type helpers | `xdr/` | Hand-written helpers in non-generated files |
+| Key encoding | `strkey/` | Decode/Encode/CheckValid |
+| Sign transactions | `keypair/` | Full.Sign(), ParseAddress() |
+| Network passphrases | `network/` | TestNetworkPassphrase, PublicNetworkPassphrase |
+| Database utilities | `support/db/` | Session, batch insert builders |
+| HTTP utilities | `support/http/` | Middleware, signed requests |
+
+## CODE MAP
+
+**Primary Public Interfaces:**
+
+| Package | Key Types/Funcs | Role |
+|---------|-----------------|------|
+| `txnbuild` | `Transaction`, `NewTransaction()`, `Operation` | Construct and sign transactions |
+| `horizonclient` | `Client`, `DefaultTestNetClient` | Query Horizon, submit transactions |
+| `rpcclient` | `Client` | Interact with Stellar RPC |
+| `ingest` | `LedgerTransactionReader`, `CheckpointChangeReader` | Parse ledger data |
+| `ledgerbackend` | `CaptiveCoreConfig`, `NewCaptive()` | Run embedded stellar-core |
+| `xdr` | All Stellar protocol types | Network data structures |
+| `keypair` | `Full`, `FromAddress`, `Parse()`, `Random()` | Key management |
+| `strkey` | `Decode()`, `Encode()`, `CheckValid()` | Address encoding |
+
+## CONVENTIONS
+
+**Deviations from standard Go:**
+- No top-level `cmd/` or `pkg/`—CLIs under `tools/`, libs at root
+- Nested `internal/` dirs (e.g., `strkey/internal/`) instead of single `/internal`
+- Many `main.go` files are NOT executables—check `package` declaration
+- Line length limit: 140 chars (relaxed)
+- Function length: up to 100 lines allowed
+
+**Error handling:**
+- Mixed stdlib `fmt.Errorf("%w", err)` and `github.com/pkg/errors.Wrap()`
+- Prefer `%w` for new code
+
+**Formatting:**
+- Run `goimports -w .` before PR (preferred over plain gofmt)
+- CI enforces via `./gofmt.sh`
+
+## ANTI-PATTERNS (THIS PROJECT)
+
+| Don't | Do Instead |
+|-------|------------|
+| Edit `xdr/xdr_generated.go` | Modify `.x` files, run `make xdr` |
+| Edit `*.pb.go` files | Modify `.proto` files, run `make generate-proto` |
+| Use `xdr.UnmarshalBinary()` on MarshalBinaryBase64 output | Use matching decode method |
+| Wrap `io.EOF` in xdr streaming | Return bare `io.EOF` |
+| Use deprecated `PathPayment` | Use `PathPaymentStrictReceive` |
+| Use deprecated `AllowTrust` | Use `SetTrustLineFlags` |
+| Use `horizon` client | Use `horizonclient` |
+
+**Generated code locations:**
+- `xdr/xdr_generated.go` — XDR types (DO NOT EDIT)
+- `gxdr/xdr_generated.go` — Alternative XDR (DO NOT EDIT)
+- `*.pb.go` files — Protobuf (DO NOT EDIT)
+
+## COMMANDS
+
+```bash
+# Format and lint (run before PR)
+./gofmt.sh && ./gomod.sh && ./govet.sh && ./staticcheck.sh
+
+# Run tests
+go test ./...                    # All tests (some need postgres)
+go test ./txnbuild              # Just txnbuild (safe)
+go test -race -cover ./...      # CI command
+
+# Regenerate XDR types
+make xdr                        # Requires Docker
+
+# Regenerate proto
+make generate-proto
+
+# Build all
+go build ./...
+
+# Run specific tool
+go run ./tools/<tool>
+```
+
+## NOTES
+
+**Test dependencies:**
+- Some tests require PostgreSQL 12+ (set `PGHOST`, `PGUSER`, etc.)
+- `ingest/ledgerbackend` tests may need stellar-core binary
+- Fuzz tests under `xdr/fuzz/`
+
+**Module path:** `github.com/stellar/go-stellar-sdk`
+
+**Go version:** 1.24+ (tests against 1.24 and 1.25)
+
+**Subdirectory AGENTS.md files exist for:**
+- `txnbuild/AGENTS.md` — Transaction building details
+- `xdr/AGENTS.md` — Generated vs manual code guidance
+- `ingest/AGENTS.md` — Ingestion library patterns
+- `clients/horizonclient/AGENTS.md` — Horizon client usage
diff --git a/clients/horizonclient/AGENTS.md b/clients/horizonclient/AGENTS.md
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+# horizonclient
+
+HTTP client for Stellar Horizon API. Query network state, submit transactions.
+
+## OVERVIEW
+
+Primary client for interacting with Horizon servers. Use with `txnbuild` for complete transaction workflow.
+
+## KEY TYPES
+
+| Type | Purpose |
+|------|---------|
+| `Client` | Main client; set `HorizonURL` |
+| `DefaultTestNetClient` | Pre-configured testnet client |
+| `DefaultPublicNetClient` | Pre-configured pubnet client |
+| `AccountRequest` | Query account details |
+| `TransactionRequest` | Query transactions |
+| `Error` | Horizon error with problem details |
+
+## COMMON PATTERNS
+
+```go
+// Use default testnet client
+client := horizonclient.DefaultTestNetClient
+
+// Or configure custom
+client := &horizonclient.Client{HorizonURL: "https://horizon.stellar.org"}
+
+// Get account
+account, err := client.AccountDetail(horizonclient.AccountRequest{
+    AccountID: "GABC...",
+})
+
+// Submit transaction (built with txnbuild)
+resp, err := client.SubmitTransaction(tx)
+// or from XDR
+resp, err := client.SubmitTransactionXDR(base64XDR)
+
+// Stream ledgers
+client.StreamLedgers(ctx, horizonclient.LedgerRequest{}, func(ledger horizon.Ledger) {
+    // handle ledger
+})
+```
+
+## REQUEST TYPES
+
+| Request | Endpoint |
+|---------|----------|
+| `AccountRequest` | `/accounts/{id}` |
+| `AccountsRequest` | `/accounts` (list) |
+| `TransactionRequest` | `/transactions` |
+| `OperationRequest` | `/operations` |
+| `EffectRequest` | `/effects` |
+| `LedgerRequest` | `/ledgers` |
+| `OfferRequest` | `/offers` |
+| `TradeRequest` | `/trades` |
+| `PathsRequest` | `/paths` |
+| `OrderBookRequest` | `/order_book` |
+| `AssetRequest` | `/assets` |
+| `ClaimableBalanceRequest` | `/claimable_balances` |
+
+## ERROR HANDLING
+
+```go
+resp, err := client.SubmitTransaction(tx)
+if err != nil {
+    if hzErr, ok := err.(*horizonclient.Error); ok {
+        // Access Horizon problem details
+        fmt.Println(hzErr.Problem.Title)
+        fmt.Println(hzErr.Problem.Extras["result_codes"])
+    }
+}
+```
+
+## ANTI-PATTERNS
+
+| Don't | Do Instead |
+|-------|------------|
+| Use deprecated `horizon` package | Use `horizonclient` |
+| Ignore `*horizonclient.Error` type | Type assert for detailed error info |
+| Hardcode Horizon URLs | Use `DefaultTestNetClient` / `DefaultPublicNetClient` |
+
+## TESTING
+
+```bash
+go test ./clients/horizonclient   # Unit tests (mocked)
+```
+
+Mock available: `horizonclient.MockClient` for testing without network.
diff --git a/ingest/AGENTS.md b/ingest/AGENTS.md
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+++ b/ingest/AGENTS.md
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+# ingest
+
+Ledger data ingestion library. Parse raw ledger data from Captive Core, RPC, or history archives.
+
+## OVERVIEW
+
+Build custom ingestion pipelines. Read transactions, state changes, and ledger metadata. Used by Horizon and custom analytics tools.
+
+## ARCHITECTURE
+
+```
+              [ Your Code ]
+                    |
+               [ Readers ]
+              /           \
+     [ChangeReader]    [TransactionReader]
+           |                    |
+    CheckpointChange      LedgerTransaction
+       Reader                 Reader
+                    |
+            [ LedgerBackend ]
+                    |
+         |---------|---------|
+      Captive    Buffered     RPC
+       Core      Storage    Backend
+```
+
+## KEY TYPES
+
+| Type | Purpose |
+|------|---------|
+| `LedgerTransactionReader` | Read transactions from a ledger |
+| `CheckpointChangeReader` | Read state changes at checkpoints |
+| `LedgerChangeReader` | Read changes within a single ledger |
+| `Change` | Represents a ledger entry change (created/updated/removed) |
+| `LedgerTransaction` | Transaction with result and metadata |
+
+## BACKENDS (`ledgerbackend/`)
+
+| Backend | Use Case |
+|---------|----------|
+| `CaptiveCoreBackend` | Run embedded stellar-core (most common) |
+| `BufferedStorageBackend` | Read from pre-exported data lake |
+| `RPCBackend` | Read from Stellar RPC |
+
+## COMMON PATTERNS
+
+```go
+// Create Captive Core backend
+backend, err := ledgerbackend.NewCaptive(ledgerbackend.CaptiveCoreConfig{
+    BinaryPath:         "/usr/bin/stellar-core",
+    NetworkPassphrase:  network.TestNetworkPassphrase,
+    HistoryArchiveURLs: network.TestNetworkhistoryArchiveURLs,
+    Toml:               captiveCoreToml,
+})
+defer backend.Close()
+
+// Prepare ledger range
+err = backend.PrepareRange(ctx, ledgerbackend.BoundedRange(1000, 2000))
+
+// Read transactions
+reader, err := ingest.NewLedgerTransactionReader(ctx, backend, passphrase, seq)
+for {
+    tx, err := reader.Read()
+    if err == io.EOF { break }
+    // Process tx
+}
+```
+
+## WHERE TO LOOK
+
+| Task | File |
+|------|------|
+| Read transactions | `ledger_transaction_reader.go` |
+| Read state changes | `checkpoint_change_reader.go`, `ledger_change_reader.go` |
+| Configure Captive Core | `ledgerbackend/captive_core_backend.go` |
+| TOML config generation | `ledgerbackend/toml.go` |
+| Buffered/lake backend | `ledgerbackend/buffered_storage_backend.go` |
+
+## ANTI-PATTERNS
+
+| Don't | Do Instead |
+|-------|------------|
+| Use `FeeChanges` directly | Use helper methods on `LedgerTransaction` |
+| Ignore `PrepareRange` | Always prepare range before `GetLedger` |
+| Skip `Close()` on backend | Defer close to avoid resource leaks |
+
+## TESTING
+
+```bash
+go test ./ingest              # Unit tests
+go test ./ingest/ledgerbackend  # Backend tests (may need stellar-core)
+```
+
+**Note:** Some tests require stellar-core binary or external services.
+
+## TUTORIALS
+
+Working examples in `ingest/tutorial/`:
+- `expiring-sac-balances/` — Track expiring Soroban balances
diff --git a/txnbuild/AGENTS.md b/txnbuild/AGENTS.md
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+++ b/txnbuild/AGENTS.md
@@ -0,0 +1,68 @@
+# txnbuild
+
+Transaction building API for Stellar network. Construct, sign, and serialize transactions.
+
+## OVERVIEW
+
+Primary SDK entry point for building transactions. Use `NewTransaction()` with operations, sign with keypairs, submit via `horizonclient`.
+
+## KEY TYPES
+
+| Type | Purpose |
+|------|---------|
+| `Transaction` | Immutable signed transaction; call `Sign()` to add signatures |
+| `TransactionParams` | Input to `NewTransaction()`: source, ops, fee, preconditions |
+| `FeeBumpTransaction` | Wrapper to increase fee on existing transaction |
+| `Operation` | Interface implemented by all 20+ operation types |
+| `Account` | Interface for source account (sequence number management) |
+| `Preconditions` | TimeBounds, LedgerBounds, MinSequence, etc. |
+
+## COMMON PATTERNS
+
+```go
+// Build transaction
+tx, err := txnbuild.NewTransaction(txnbuild.TransactionParams{
+    SourceAccount:        &account,
+    IncrementSequenceNum: true,
+    Operations:           []txnbuild.Operation{&op},
+    BaseFee:              txnbuild.MinBaseFee,
+    Preconditions:        txnbuild.Preconditions{TimeBounds: txnbuild.NewTimeout(300)},
+})
+
+// Sign (returns NEW Transaction - immutable)
+tx, err = tx.Sign(network.TestNetworkPassphrase, keypair)
+
+// Serialize for submission
+xdrBase64, err := tx.Base64()
+```
+
+## WHERE TO LOOK
+
+| Task | File |
+|------|------|
+| Create transaction | `transaction.go` — `NewTransaction()` |
+| Payment operation | `payment.go` |
+| Path payments | `path_payment_strict_send.go`, `path_payment.go` |
+| Account creation | `create_account.go` |
+| Trust lines | `change_trust.go`, `set_trust_line_flags.go` |
+| Offers/DEX | `manage_offer.go`, `manage_buy_offer.go` |
+| Soroban invoke | `invoke_host_function.go` |
+| Fee bumps | `transaction.go` — `NewFeeBumpTransaction()` |
+
+## ANTI-PATTERNS
+
+| Don't | Do Instead |
+|-------|------------|
+| Use `PathPayment` | Use `PathPaymentStrictReceive` (renamed) |
+| Use `AllowTrust` | Use `SetTrustLineFlags` |
+| Mutate Transaction after Sign | Transaction is immutable; Sign returns new instance |
+| Forget `IncrementSequenceNum` | Set `true` unless managing sequence manually |
+
+## TESTING
+
+```bash
+go test ./txnbuild           # Unit tests (no external deps)
+go test ./txnbuild -v        # Verbose
+```
+
+Demo available: `go run ./txnbuild/cmd/demo`
diff --git a/xdr/AGENTS.md b/xdr/AGENTS.md
new file mode 100644
index 0000000000..3233c5b9ae
--- /dev/null
+++ b/xdr/AGENTS.md
@@ -0,0 +1,76 @@
+# xdr
+
+Stellar XDR (External Data Representation) types. **MOSTLY GENERATED CODE.**
+
+## OVERVIEW
+
+Contains all Stellar protocol types: transactions, operations, ledger entries, assets, etc. The bulk is generated from `.x` IDL files—do NOT edit generated code.
+
+## GENERATED vs MANUAL
+
+| File | Type | Edit? |
+|------|------|-------|
+| `xdr_generated.go` | Generated | **NO** — 50k+ lines, regenerate via `make xdr` |
+| `Stellar-*.x` | IDL source | Yes — modify these, then regenerate |
+| All other `*.go` | Hand-written helpers | Yes |
+
+**Hand-written helpers** (safe to edit):
+- `asset.go`, `account_id.go`, `muxed_account.go` — type helpers
+- `json.go` — JSON marshaling customization
+- `scval.go` — Soroban value helpers
+- `ledger_key.go`, `ledger_entry.go` — ledger data helpers
+- `transaction_envelope.go` — envelope manipulation
+- `xdrstream.go` — streaming XDR reader
+
+## REGENERATION
+
+```bash
+# Requires Docker
+make xdr
+
+# Or step by step:
+# 1. Edit xdr/Stellar-*.x files
+# 2. Run make xdr (uses xdrgen via Docker)
+# 3. Commit xdr_generated.go
+```
+
+## COMMON PATTERNS
+
+```go
+// Decode base64 XDR
+var envelope xdr.TransactionEnvelope
+err := xdr.SafeUnmarshalBase64(base64Str, &envelope)
+
+// Encode to base64
+base64Str, err := xdr.MarshalBase64(envelope)
+
+// Stream reading (for large data)
+reader := xdr.NewXdrStream(r)
+for {
+    var entry xdr.LedgerEntry
+    err := reader.ReadOne(&entry)
+    if err == io.EOF { break }
+}
+```
+
+## ANTI-PATTERNS
+
+| Don't | Do Instead |
+|-------|------------|
+| Edit `xdr_generated.go` | Edit `.x` files, run `make xdr` |
+| `xdr.UnmarshalBinary()` on base64 data | Use `xdr.SafeUnmarshalBase64()` |
+| Wrap `io.EOF` in stream reading | Return bare `io.EOF` for proper termination |
+| Use deprecated `LedgerKey.LedgerKey()` | Use `LedgerEntryData.LedgerKey()` |
+
+## FUZZ TESTING
+
+Fuzz harnesses under `xdr/fuzz/`:
+- `jsonclaimpredicate/` — JSON claim predicate fuzzing
+- Corpus files for reproducible fuzzing
+
+## NOTES
+
+- XDR commit tracked in `xdr_commit_generated.txt`
+- gxdr package (`../gxdr/`) is alternative XDR impl—also generated
+- Many types have `MarshalBinary`/`UnmarshalBinary` for wire format
+- JSON marshaling customized for Horizon API compatibility