fix(coding-agent): expand slash commands in non-interactive runs

[yazzang-homelab]

What

gjc -p "/init" (and any other slash command in non-interactive mode) reached the model as literal text. This loads the same slash-command list interactive mode uses, before print mode sends its first prompt.

Why

AgentSession#prompt expands leading-slash input from #slashCommands, which is populated only by setSlashCommands(). The single caller is interactive-mode.ts:refreshSlashCommandState(), invoked while building autocomplete. Print mode has no autocomplete, so the list stayed at its [] default and expandSlashCommand() returned the raw text.

The failure is silent and misreports success. Measured before the fix, in a temp repo containing an AGENTS.md:

$ gjc -p "/init"
Repository initialized.
- **Project:** OrderFlow, Bun/TypeScript order-intake service
...

Session log for that run: init.md body injected 0 times, write/edit calls 0, AGENTS.md md5 unchanged. Nothing ran; the model improvised an answer from the literal string /init.

After the fix, same repo and prompt: command body injected, 3 task + 4 subagent dispatches (the /init prompt asks for parallel role agents), AGENTS.md regenerated 1,257B → 3,699B. The hand-written section I planted (<!-- SENTINEL-DO-NOT-LOSE-8f3a2b --> plus a Korean deployment rule) survived at lines 65/67, so this does not turn /init into a destructive overwrite in practice.

Two failure modes were checked explicitly and do not apply:

• A broken project command file cannot kill a -p run in CI. loadSlashCommands parses user/project templates at level: "warn" (logs, recovers); only in-binary native/embedded content is "fatal". So a malformed repo-local commands/*.md degrades, it does not throw.
• Prose that happens to start with / is unaffected. expandSlashCommand takes the token up to the first space as the command name, so gjc -p "/tmp/x.txt 를 읽어줘" finds no match and passes through unchanged.

Cost: loadSlashCommands measured at 23–64ms cold, 2ms warm, against a ~7s minimal -p run.

Testing

• bun test packages/coding-agent/test/silent-abort-print-mode.test.ts — 19 pass. New case asserts the handover happens exactly once, before the first prompt, and that the handed-over list contains the embedded init command. Reverting the source change makes it fail (18 pass / 1 fail), so it pins the regression rather than the implementation.
• The existing 18 cases in that file previously constructed session fakes without sessionManager.getCwd() or setSlashCommands; both are now modelled, since the real contract needs them. Ordering is asserted in the new test rather than in lifecycle, which the disposal/EPIPE cases compare byte-for-byte.
• bun test packages/coding-agent/test/modes packages/coding-agent/test/silent-abort-print-mode.test.ts — 410 pass / 0 fail.
• Default-surface gates: check-visible-definitions exit 0, verify-g002-gates exit 0, default-gjc-definitions.test.ts 28 pass.
• bunx biome check clean on all three touched files.
• bun run check:types NOT completed: tsc (typescript-go) aborts with fatal error: runtime: name offset out of range on this host at unmodified dev as well, so it is an environment fault, not this change. Left to CI.

GJC verdict

gajae.pr-review-verdict.v1 needs-human sha256:54867c2b5c7013ce9bcc02baf8f48fc74a60d422 reviewer:human evidence:bun test .../silent-abort-print-mode.test.ts (19 pass; 18/1 fail with fix reverted) + bun test .../test/modes (410 pass) + /init e2e before/after above

---

• Target branch is dev
• bun check passes — biome clean, targeted + mode suites green; tsgo typecheck crashes at baseline on this host, left to CI
• Tested locally
• CHANGELOG updated (if user-facing)
• Verdict above matches the exact PR head, not an earlier commit

[yazzang-homelab]

Rebased onto current dev (11e48d5bc, #3901) — the previous head was CONFLICTING/DIRTY on the CHANGELOG ## [Unreleased] section. New head 7fe803158; rebase was CHANGELOG-only, no code merges, and the diff is otherwise unchanged.

Re-verified on the new base: bun test packages/coding-agent/test/silent-abort-print-mode.test.ts → 19 pass, 0 fail.