A hand-written `[sponsors] enabled = false` is undone after one config save and reload

[ianalitis]

Source commit: 983b53270 (upstream master, 2026-09-06; repair_frozen_sponsors_optout unchanged)
Upstream: https://github.com/1jehuang/jcode
Binary identity: jcode v0.81.66-dev (0d008c720)
Platform: macOS 26.6.2, arm64

Summary

Writing [sponsors]\nenabled = false by hand into config.toml is respected on
the next load, but the opt-out disappears after any process saves config and a
later load reads it back. Observed twice on this host (2026-09-05 13:xx append,
gone by 22:26; re-appended, would have been lost on the next save).

Cause (from source)

1. Config::save (crates/jcode-base/src/config/config_file.rs) serializes the
   whole struct. sponsors_is_default (config.rs:837) skips the table only when
   enabled is true, so an opt-out is written back as two keys:
   enabled = false plus the default endpoint.
2. repair_frozen_sponsors_optout (config_file.rs:79) treats exactly that
   shape, two keys with enabled = false and a default endpoint, as a
   machine-frozen legacy value and resets it to SponsorsConfig::default()
   (enabled) in memory.
3. The following save omits the now-default table. The user's opt-out is gone.

The heuristic cannot distinguish "hand-written opt-out round-tripped once through
save" from "frozen by the legacy default". Every hand-written opt-out becomes the
former after the first save.

Reproduction

printf '\n[sponsors]\nenabled = false\n' >> ~/.jcode/config.toml
grep -A2 '^\[sponsors\]' ~/.jcode/config.toml   # table absent

Expected

An explicit enabled = false survives save and reload indefinitely.

Proposed fix

Either serialize the opt-out as the single key the user wrote (skip endpoint
when it equals the default), or mark the repair with a one-time migration flag
instead of inferring it from table shape. A regression test: write
[sponsors] enabled = false, load, save, load, assert enabled == false.

Workaround in use

Pair the opt-out with a non-default endpoint, which the heuristic respects:

[sponsors]
enabled = false
endpoint = "http://127.0.0.1:1"

[1jehuang]

Thanks for the report. Explicit sponsor opt-outs now survive configuration save/load and unrelated preference updates.

Proposed fix: #1218, commit 17f57b0. All eight sponsor configuration tests passed.

The PR remains a draft pending clean-branch CI and review. It documents the local build limitations. This issue remains open until the fix is merged and verified.

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— Jcode agent (automated triage), on behalf of @1jehuang