Reconcile the rewrite decision with the integration that shipped without it

[blooop]

Three records currently disagree about how wf should consume devlaunch, and nothing points at the disagreement:

record	says
devlaunch#53	GO — devlaunch-core crate + dl bin, linked into wf. Subprocess-on-PATH rejected.
CHANGELOG.md [Unreleased]	Rewrite deferred, Python remains, no cutoff to plan around.
blooop/wayfinder#80	Subprocess on PATH. "Rewriting devlaunch in Rust" out of scope — reinforced.

docs/rust-port-scope.md puts them side by side, adds the measurements neither argument had, and narrows the live question to #53's own falsifier.

What is new since #53, and it is evidence rather than opinion: #53's central claim was that the crate wins because a breaking change fails wf's build, where subprocess drift is silent until runtime. That has now happened — wf 0.14.0 prewarms with dl <workspace> up, which no released dl had until 0.0.24 (#175). Neither repo's CI caught it. wf now carries a runtime version floor, which is the strongest thing a subprocess seam can do and strictly weaker than what #53 promised.

Measured, not argued:

• The 370 MB environment is 275 MB CPython + 118 MB devpod + 84 KiB devlaunch. A Rust port lands at ~120 MB and devpod is 118 MB of it — the floor is devpod, not the language.
• ~60 MB of it (tk, icu) is conda-forge's python build, not anything dl asks for. Cheapest size win on the list, and not a Rust win.
• The port is 7,373 lines of source against 18,039 lines of tests, of which the 61 mock-free acceptance tests port and the 376 mock-based ones are read as a spec.

No decision is taken here. The recommendation is to reopen #53 with one question — does wf render per-ticket workspace state? — and to record the answer in both repos, since the two places that went out of sync are wayfinder#80's out-of-scope line and this changelog's deferral paragraph.

🤖 Generated with Claude Code

Summary by Sourcery

Document the current scope, tradeoffs, and open questions around a potential Rust port of devlaunch and its integration with wf.

Documentation:

• Add a scoping note detailing the conflicting records about the devlaunch Rust rewrite, the existing subprocess-based integration in wf, and the implications of that mismatch.
• Record measured data on environment size, code and test volume, and performance to ground future decisions about a Rust port.
• Clarify the actual decision to be made about how wf should consume devlaunch, including when a Rust crate integration would be warranted, and recommend reopening issue Decide: Rust rewrite — go or no-go #53 with a narrower, state-rendering focused question.

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[sourcery-ai]

Reviewer's Guide

Adds a new architectural/scoping document that reconciles conflicting decisions about how wf integrates with devlaunch, documents empirical evidence from recent releases, and frames the remaining decision around whether wf needs typed access to per-workspace state versus a subprocess contract.

Sequence diagram for wf prewarm with devlaunch version floor

sequenceDiagram
    participant wf as wf_0_14_0
    participant dl as dl_cli

    wf->>dl: dl --version
    dl-->>wf: 0.0.23 or 0.0.24

    alt [dl_version >= 0.0.24]
        wf->>dl: dl <workspace> up
        dl-->>wf: prewarm complete
    else [dl_version < 0.0.24]
        wf-->>wf: degrade to host launch (record dl below floor)
    end

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File-Level Changes

Change	Details	Files
Introduce a Rust port scoping document that reconciles prior design records and frames the remaining decision.	Describe the three conflicting records (devlaunch#53, CHANGELOG deferral, wayfinder#80 subprocess decision) and how they relate to the current shipped integration. Document the empirical drift incident between wf and dl (the up command) and the resulting introduction of a runtime version floor and conda run dependency. Provide concrete measurements for environment size, code and test footprints, and performance characteristics to clarify the real costs/benefits of a Rust rewrite versus keeping Python. Clarify what is actually being decided (subprocess vs crate seam given workspace state rendering) and recommend reopening devlaunch#53 with a narrower, evidence-based question recorded consistently in both repos.	docs/rust-port-scope.md

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.95%. Comparing base (bb7f821) to head (e7795fb).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #176   +/-   ##
=======================================
  Coverage   93.95%   93.95%           
=======================================
  Files          21       21           
  Lines        2565     2565           
=======================================
  Hits         2410     2410           
  Misses        155      155           

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