dev-instance --fake-im: drive bound-app IM intake on a real Host without a real platform #1118

v1.3 release topology — 2026-10-11

Parent: #48 (native sub-issue relationship verified). Project #10; target milestone v1.3. Preserve the existing implementation/qualification scope, claims, accepted evidence and runtime authorization. Native parentage is coordination, not an additional execution blocker.

Problem

To verify IM intake (bind app → DM / @mention → implicit conversation entry → Inbox → model → reply), you need a real IM app today. A cloud agent cannot reach one, so changes like #1108/#1112 were checked only by unit tests and by screenshots built from sample data injected into the client.

Slice

• scripts/dev-fake-im.mjs: a development-only fake dshIm Provider (feishu / slack / discord / weixin). It implements the same public contract that createDshImProvider validates. Messages go in through a spool directory, and replies are written to an outbox.
• node scripts/dev-instance.mjs ... --fake-im [platform] inserts that Provider through a launch Patch.
• dev-fake-im.mjs bind binds the fake app to a Bot. dev-fake-im.mjs send [--group [--no-mention]] <text> delivers one message and prints the reply.
• A contract test runs the fake through the real adapter and core intake.

Only the IM platform is simulated. Real-platform QA (--im-provider, Human QA) stays separate.

Verified on 2026-10-07 from a cloud session: a real DSH 0.2.0-rc.1 Host with OpenCode Go got a DM reply in ~3 s and a group @mention reply in ~3 s, and unmentioned chatter was not admitted.