fix(config): reject malformed cross_project_learnings at set

[szsunyuan]

Why (in your own words)

gstack-config set cross_project_learnings ture exited 0 and stored the typo. Skills only enable on the literal true, and a non-empty value suppresses the first-run prompt, so the feature stayed off and the question never came back. The official AskUserQuestion path only writes true / false. A hand-typed typo was the hole.

Reject the bad write, same as codex_reviews. Do not coerce to false — a stored default still kills the empty-get sentinel.

Fixes #2673. Same class as #2488 (durable bad write). Not #1726 / #1723 (those are parseInt on one-shot flags; #1726 is already on main, #1723 has #1724). Did not add an unset token or a new subcommand.

Why this shape

Issue author named bin/gstack-config set and the closed-domain block. CONTRIBUTING's wave rule: if two PRs fix the same thing, keep the smaller one. This is 2 files, on current main. Fine to absorb into a wave.

Did not follow the issue's "Expected" pair_agent warn-and-default. That would persist a value and still suppress the prompt.

What it does

• set cross_project_learnings accepts only true and false.
• Anything else exits 1, prints not recognized, leaves the file unchanged.
• Empty get (first-run sentinel) is unchanged.

What it deliberately does not do

• Accept literal unset (author snippet; optional undo, not the typo bug)
• Add gstack-config unset
• Heal an already-stored ture on get
• Whitelist skill_prefix / telemetry / other unvalidated keys
• Extract validate_key() (TODOS P3 leftover)
• VERSION / CHANGELOG / README / ETHOS
• /ship (wave stamps version)

AI was used for assistance.

Live evidence

Temp GSTACK_HOME only — not ~/.gstack/config.yaml. Same isolated dir, real bin/gstack-config.

Before (upstream/main @ 85fd9db):

$ bin/gstack-config set cross_project_learnings ture
$ echo $?
0

$ bin/gstack-config get cross_project_learnings
ture

After (this branch):

$ bin/gstack-config set cross_project_learnings ture
Error: cross_project_learnings 'ture' not recognized. Valid values: true, false. Existing value left unchanged.
$ echo $?
1

$ bin/gstack-config get cross_project_learnings

$ echo $?
0

$ bin/gstack-config set cross_project_learnings true
$ bin/gstack-config get cross_project_learnings
true

$ bin/gstack-config set cross_project_learnings ture
Error: cross_project_learnings 'ture' not recognized. Valid values: true, false. Existing value left unchanged.
$ bin/gstack-config get cross_project_learnings
true

Scope

• Changed: bin/gstack-config (set only), test/gstack-config-cross-project.test.ts
• Verified live by: the transcripts above, plus bun test test/gstack-config-cross-project.test.ts test/gstack-config-defaults.test.ts test/gstack-config-redact-keys.test.ts test/gstack-config-key-locale.test.ts (18 pass). The two reject cases were red on tip (Expected: 1, Received: 0) before the arm existed. Full bun run test green (7 shards). bun run slop:diff: no new findings in 2 files.
• Did NOT test: Tier 2/3 evals. A real ~/.gstack/config.yaml. Healing a ture already on disk (out of scope).

Liveness proof (required)

• Liveness screenshot attached: GSTACK PR typed live into a real surface (not edited onto the image)

Checklist

• Liveness screenshot attached: GSTACK PR typed live into a real surface (not edited onto the image)
• This is not a generated-file-only diff (I edited the source, not a generated SKILL.md)
• No ETHOS.md edits, and no changes to voice / founder perspective / YC references
• New public command / external service / host adapter has an accepted issue linked (or N/A)
• Linked issue or reproduction: gstack-config accepts malformed cross_project_learnings values, silently disabling cross-project learnings with no supported way to undo it #2673

Test plan

• bun test test/gstack-config-cross-project.test.ts → 4 pass (2 were red on tip)
• Live: set ture → exit 1, get empty
• Live: set true then set ture → still true
• Empty get sentinel still exit 0
• Existing defaults / redact / locale config tests still pass

Fork PRs do not get eval secrets; the free file above is the gate.

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