Feature: Propose dev-fastforward preset with /advance-ledgers endpointCreate proposal-dev-fastforward.md

[LiamVanderdeg]

Summary

Proposal for a dev-fastforward preset implementing the endpoint requested by @teddav in #932:
"An endpoint to automatically advance by N ledgers" for local Soroban testing.

Problem

As described in #932:

1. Local --local mode starts at ledger 1, unlike testnet/mainnet where ledgers are in the millions.
2. The current workaround with ENABLE_CORE_MANUAL_CLOSE=true + /manualclose is slow when horizon/rpc are enabled.
3. Disabling horizon to speed up causes friendbot to crash and take down the container.
4. Env vars like STELLAR_CORE_FLAGS, ENABLE_FRIENDBOT are inconsistently supported across image versions.

Proposed Solution

Add --preset dev-fastforward that:

• Enables --core-config-unsafe-mode to disable archive publishing/validation
• Disables horizon/rpc/friendbot by default during fast-forward
• Exposes /advance-ledgers?count=N endpoint as requested by @teddav

This allows reaching ledger 1M+ in minutes, matching real network conditions for time-based contract testing.

Context

This PR formalizes the discussion in issue #932 and the solution we use for chathapop.app testing,
which cuts local test time ~90%.

Reference: #932

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a written proposal describing a new dev-fastforward preset and an /advance-ledgers endpoint to speed up local Soroban testing by fast-forwarding ledgers.

Changes:

• Introduces a proposal doc for a dev-fastforward preset.
• Documents rationale and constraints from issue #932.
• Specifies intended behavior (unsafe core mode, disabling services, new endpoint).

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[LiamVanderdeg]

Ecosystem contribution: Proposed dev-fastforward preset per issue #932

[LiamVanderdeg]

@leighmcculloch Branch updated and marked ready for review.Thanks!

[github-actions]

This pull request is stale because it has been open for 90 days with no activity.

[LiamVanderdeg]

Hi team - quick polite ping to keep this PR active and remove the stale label.

This proposal has been ready for review for a while and I kept it rebased on main (xdr v27.0.0). The complete check is still showing Waiting for status to be reported, which I believe needs a workflow approval for external contributors.

The proposal fixes #932 and is documented in commit 1761f67 with implementation notes on security (404 by default, only enabled with UNSAFE_FASTFORWARD=true for local dev).

I have a working implementation ready that cuts local test time by ∼90% for time-based testing and I'm happy to push it here once CI is unblocked.

No rush, just wanted to keep this from auto-closing and check if there's any feedback on the approach. Thanks for maintaining quickstart!

[leighmcculloch]

Hi team - quick polite ping to keep this PR active and remove the stale label.

This proposal has been ready for review for a while and I kept it rebased on main (xdr v27.0.0).

We use PRs for code changes, so we don't have a process to keep the PR active that isn't being reviewed for merging. I'm updating this PR to a draft since it's not intended for merging.

check if there's any feedback on the approach

Posting thoughts on the issue: #932.