> For the complete documentation index, see [llms.txt](https://soroban-cost-estimator.gitbook.io/soroban-cost_estimator-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://soroban-cost-estimator.gitbook.io/soroban-cost_estimator-docs/verification.md).

# Verification

The invocation path is proven end-to-end against a **real deployed contract** on Stellar testnet, cross-checked against the native Stellar CLI. This page reproduces the record in full so a skeptical reader can re-verify without digging through the repository. The canonical record lives in [`tests/fixtures/contract/README.md`](https://github.com/aigbagbobila/soroban-cost-estimator/blob/main/tests/fixtures/contract/README.md).

## The contract

* **Source**: `tests/fixtures/contract/src/lib.rs` — `increment(env, step: i64) -> i64`, reads a stored counter, adds `step`, writes it back. The storage write gives `simulateTransaction` a non-trivial footprint (rent / refundable fee portion), so fee breakdowns are realistic.
* **Fixture binary**: `tests/fixtures/contract.wasm`, SHA-256 `ea14bca998e98f0ddb338e8e5cef6e19f07378a3b71e8b4f8868cedc857e4ecd`. This is the exact WASM deployed to testnet — the tool's cached estimate for the deployed contract carries the same `wasm_hash`.

## Live testnet deployment

| Field       | Value                                                                                                                                       |
| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| Network     | testnet                                                                                                                                     |
| Contract ID | `CC4WIEYYSCFGDJXMLZ73FKUUJNDEOJRNOOBZHI55QR27NW4RCNTHAQ5T`                                                                                  |
| Deploy tx   | `d89a51f0…` ([stellar.expert](https://stellar.expert/explorer/testnet/tx/d89a51f0c0c1c7d9a0497a59ec17611605e4e50401e9deccf8df2fe8de2ab6ef)) |

## Cross-check numbers — this tool vs `stellar contract invoke --cost`

Call: `increment(step=5)` on testnet, ledger \~3,898,1xx.

| Metric                       | This tool | Native CLI              | Divergence     |
| ---------------------------- | --------- | ----------------------- | -------------- |
| CPU instructions             | 524,389   | 524,389                 | **0%** (exact) |
| Total resource fee (stroops) | 18,999    | 18,999 (±1 across runs) | **≤0.011%**    |
| Read / Write entries         | 1 / 1     | 1 / 1                   | 0              |
| Write bytes                  | 136       | 136                     | 0              |
| Tx size (XDR bytes)          | 156       | (same envelope)         | —              |

The \~20% margin `simulateTransaction` itself applies is a buffer convention; this run landed at ≤0.011% (a 1–2 stroop run-to-run rent variance, not a math error — an earlier run \~40–50 ledgers prior reported 19,001).

### Re-verification on a later ledger (2026-08-04)

Re-running the same invocation months later (ledger 3,961,544) reproduced the structural numbers exactly and the fee within the documented margin:

| Metric                       | 2026-08-04 run | Original | Match                                 |
| ---------------------------- | -------------- | -------- | ------------------------------------- |
| CPU instructions             | 524,389        | 524,389  | exact                                 |
| Read / Write entries         | 1 / 1          | 1 / 1    | exact                                 |
| Write bytes                  | 136            | 136      | exact                                 |
| Tx size (XDR bytes)          | 156            | 156      | exact                                 |
| Total resource fee (stroops) | 17,122         | 18,999   | within \~20% margin (rate/rent drift) |

The native CLI `transaction_data` XDR (base64) from the original run, for independent re-verification:

```
AAAAAAAAAAEAAAAH6hS8qZjpjw3bM46OXO9uGfBzeKO3HotPiGjO3IV+Ts0AAAABAAAABgAAAAG5ZBMYkIphpuxef7KqlEtGRyYtc4OTo72EdfbbkRNmcAAAABQAAAABAAgAZQAAAAAAAACIAAAAAAAASjc=
```

(Tail layout: `instructions u32` → `read_bytes u32` → `write_bytes u32` → `resource_fee i64` = the last 20 bytes.)

## Reproduction steps

```bash
# 1. Build the fixture
cd tests/fixtures/contract && ./build.sh && cd ../../..

# 2. Install the WASM on testnet (capture the printed wasm hash)
stellar contract install --network testnet --source test-key \
  --wasm tests/fixtures/contract.wasm

# 3. Create the contract instance (or reuse the ID below)
stellar contract create --network testnet --source test-key \
  --wasm-hash <wasm-hash> \
  --id CC4WIEYYSCFGDJXMLZ73FKUUJNDEOJRNOOBZHI55QR27NW4RCNTHAQ5T

# 4. Estimate with this tool
soroban-cost-estimator estimate \
  --wasm tests/fixtures/contract.wasm \
  --id CC4WIEYYSCFGDJXMLZ73FKUUJNDEOJRNOOBZHI55QR27NW4RCNTHAQ5T \
  --network testnet --fn increment --arg step=5 --json

# 5. Cross-check with the native CLI (simulate-only, nothing submitted)
stellar contract invoke --network testnet \
  --id CC4WIEYYSCFGDJXMLZ73FKUUJNDEOJRNOOBZHI55QR27NW4RCNTHAQ5T \
  --source-account test-key --send=no --cost --very-verbose \
  -- increment --step 5
```

Compare step 5's `instructions` and `resource_fee` / `min_resource_fee` with step 4's `cpu_instructions` and `fee.total_stroops`. They should land within \~20% (the margin `simulateTransaction` itself applies); this fixture reproduces ≤0.011%. The output format of step 4 is shown verbatim on the [`estimate`](/soroban-cost_estimator-docs/estimate.md) page.


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