docs(agent): #128 — 14d prune for system and Home Manager gens

Same floor (keep current + ≥3 past); age window 14 days not 30; apply
independently to system and HM profiles.

agent/BACKLOG.md

@@ -78,40 +78,43 @@ cable leaves. Capture steps in HARDWARE-QUEUE.
 
 ## NEXT
 
-### 128. Auto-prune NixOS generations: >30 days, but keep ≥3 past
+### 128. Auto-prune system + HM generations: >14 days, but keep ≥3 past
 
-Bernardo 2026-07-15: automatic cleanup of **NixOS** (system) generations
-so the boot menu and store do not grow without bound, with a safety floor:
+Bernardo 2026-07-15 (refined same day): automatic cleanup of **both**
+NixOS (system) and Home Manager (per-user) generations so boot menu,
+desktop rollback, and store do not grow without bound, with a safety floor:
 
-1. **Age:** candidates older than **30 days** may be removed.
+1. **Age:** candidates older than **14 days** may be removed.
 2. **Count floor:** always keep the **current** generation and at least
-   **3 past** generations — even if those three are older than 30 days.
-3. Combined: delete only gens that are **both** older than 30 days **and**
-   older than the third-most-recent past generation. Gens within 30 days
+   **3 past** generations — even if those three are older than 14 days.
+3. Combined: delete only gens that are **both** older than 14 days **and**
+   older than the third-most-recent past generation. Gens within 14 days
    stay regardless of how many there are (until they age out).
+4. **Apply the same rule independently** to the system profile and to each
+   user's Home Manager profile (desktop rollback in Recovery › Desktop).
 
 **Why this shape:** pure age GC (`--delete-older-than`) can wipe a machine
 that is rarely rebuilt down to one generation and remove useful rollback
 targets; pure count limits (`configurationLimit`) drop recent work just
 because the user iterates a lot. Age + floor keeps travel-laptop machines
-safe and busy desktops tidy.
+safe and busy desktops tidy. 14d matches the existing store GC cadence
+rather than a longer 30d hold.
 
 **Today:** `nix.gc` is already weekly with `--delete-older-than 14d`
-(`modules/nixos/default.nix`) — store GC, no min-generation floor, and
-14d not 30d. This item should replace/refine that policy (or add a
-dedicated generation pruner if stock GC cannot express the floor).
+(`modules/nixos/default.nix`) — store GC, **no** min-generation floor, and
+it is not framed as an explicit dual system+HM policy. This item should
+replace/refine that (or add a dedicated pruner if stock GC cannot express
+the floor on both profiles). Bootloader list
+(`boot.loader.systemd-boot.configurationLimit`) may need to stay in sync
+so removed system profiles do not leave dead boot entries.
 
-**Scope (settle if needed):** system profile only vs also Home Manager
-user generations (desktop rollback in Recovery). Bootloader list
-(`boot.loader.systemd-boot.configurationLimit`) may need to stay in
-sync so removed profiles do not leave dead boot entries.
-
-Pass = weekly (or post-rebuild) cleanup enforces 30d + keep ≥3 past on
-system generations; a machine with only old gens never goes below
-current+3; docs/RECOVERY still matches the boot-menu story; doctor or a
-check asserts the timer/unit exists and the prune script's dry-run
-logic. V3: run on a box with many gens and confirm boot menu +
-`nix-env -p /nix/var/nix/profiles/system --list-generations`.
+Pass = weekly (or post-rebuild) cleanup enforces 14d + keep ≥3 past on
+**system and HM** generations; a machine with only old gens never goes
+below current+3 on either profile; docs/RECOVERY still matches boot-menu
+and desktop rollback; doctor or a check asserts the timer/unit exists and
+the prune script's dry-run logic. V3: box with many gens — boot menu +
+`nix-env -p /nix/var/nix/profiles/system --list-generations` +
+`home-manager generations` after a prune.
 
 ### 120. A netinstall ISO, next to the fat offline one
 

agent/JOURNAL.md

@@ -20,12 +20,12 @@ Template:
 ---
 
 ## 2026-07-15 — File #128 generation auto-prune policy (no code)
-- **Task:** Bernardo: auto-clean NixOS gens older than 30 days but always
-  keep ≥3 past generations.
-- **Did:** NEXT **#128**. Policy restated; noted existing `nix.gc` weekly
-  `--delete-older-than 14d` has no min-generation floor.
+- **Task:** Bernardo: auto-clean gens older than N days but always keep
+  ≥3 past; include HM; prefer 14d over 30d.
+- **Did:** NEXT **#128** — system **and** Home Manager; **14 days** + keep
+  ≥3 past. Noted existing `nix.gc` weekly 14d has no min-generation floor.
 - **Verified:** V0 (docs/agent only).
-- **Pending:** implement when picked; optional HM gens scope.
+- **Pending:** implement when picked.
 - **Next suggestion:** implement #128, or human #115/#120.
 
 ## 2026-07-15 — #111 Recovery + #105 System IA + #110 retire Control Center