host: two different paths print the same ~/state.json once a nested home is abbreviated #2956

Implementation: FlyBot (ours) — PR follows within 24h. Do not pick up without a pickup-ok comment on this issue.

Written-by: FlyBot Lead
Claimed-by: FlyBot Lead
Claim-Id: 6ee20587cfc247209db2c0680e43dca4
Branch: dev/3-nested-home-collision
Base: 54054fb
At: 2026-11-12T06:58:57Z

Implementation: FlyBot (ours) — PR follows within 24h. Do not pick up without a pickup-ok comment.

Written-by: FlyBot Lead
Found-by: FlyBot Test (advisory on #2947); evidence reproduced on live main.

What happens

Since #2947, the diagnostics report abbreviates every home it prints. In the normal layout — the DSH home sits under the OS home — the nested DSH home collapses onto ~ as well, so two different files in one report render identically:

• the state file: row for a file at the OS home root prints ~/state.json;
• a host entry line for a file inside the DSH home prints ~/state.json too.

Before #2947, the second one printed ~/.dsh/bot/state.json-style (the OS-home prefix only), so a reader could tell the two apart. Test's reading: …/os-home/state.json and …/os-home/.dsh-p2947/bot/state.json both draw ~/state.json in one report; on base 6af7d044 the second still read ~/.dsh-p2947/bot/state.json.

Why it matters

The report is the artefact people paste into a bug report. Two different paths printing the same string makes "which file is this?" unanswerable exactly where the report is supposed to answer it.

Expected

A report must never print the same string for two different paths. Keep abbreviating: the OS home still becomes ~, and a DSH home outside the OS home still becomes ~ — but a DSH home inside the OS home must keep the part that distinguishes it (for example ~/.dsh/bot/state.json rather than ~/state.json), and the same rule must apply on the Read-only row and on entry lines. The length bound still applies after abbreviation, and the trailing instruction (fix or move the file and reload / close the other one and reload) must survive.

Reproduction

DSH_HOME under the OS home (normal layout), a live state.lock plus a state.json that is a directory, then diagnostics.report(): grep the markdown for the pair of paths — today both render ~/state.json.

Scope

core/src/host/diagnostics.js (the home-abbreviation set and its ordering), core/test/diagnostics.test.js (one case pinning that the two paths stay distinguishable), and the regenerated patches/ds-bot/0001-core-fixes.patch. No client bundle, no patches/ds-bot/0008.

Dedupe (2026-11-12, open + closed)

nested home / home abbreviated report nested return only #2936/#2938/#2944/#2947 (all closed, all about abbreviating or bounding, none about two paths colliding); no open issue or PR covers the collision. No same-shape issue.