Validate side-by-side FreeBSD source revisions

docs/PROGRESS.md

@@ -1,5 +1,64 @@
 # Progress
 
+## 2026-04-03 — Phase 17.1 completed: side-by-side FreeBSD source revisions now coexist in `/frx/store`
+
+Completed work:
+
+- added Phase 17 operating-system templates for distinct source identities:
+  - `tests/system/phase17-git-source-operating-system.scm.in`
+  - `tests/system/phase17-txz-source-operating-system.scm.in`
+- modeled the Git side with both:
+  - ref: `stable/15`
+  - pinned commit:
+    - `332708a606f6bf0841c1d4a74c0d067f5640fe89`
+- modeled the archive side with:
+  - `https://download.freebsd.org/releases/amd64/15.0-RELEASE/src.txz`
+  - sha256:
+    - `83c3e8157b6d7afcae57167fda75693bf1e5f581ca149a6ecb2d398b71bdfab0`
+- added side-by-side source coexistence validation:
+  - `tests/system/run-phase17-source-coexistence.sh`
+- the new harness builds:
+  - Git source build A
+  - `src.txz` source build
+  - Git source rebuild B
+  and verifies:
+  - Git rebuild stability when pinned by commit
+  - distinct closure paths for Git vs `src.txz`
+  - distinct materialized source stores
+  - distinct native kernel/bootloader/runtime outputs
+  - correct declared/materialized source metadata in closures and native build info
+  - continued use of the materialized source root instead of the unused declared transitional `source-root`
+- wrote:
+  - `docs/reports/phase17-side-by-side-source-revisions-freebsd.md`
+
+Validation:
+
+- `PASS phase17-source-coexistence`
+- validated side-by-side closures:
+  - Git closure:
+    - `/frx/store/d6cbcc76f57fa9c392a80fe20e7499f7a837aab4fb96ea056e624cde95bc70c8-fruix-system-fruix-freebsd`
+  - `src.txz` closure:
+    - `/frx/store/02268e19930facb32e12b6ec191f2e5704d1e81033baf3637a889ad15924ff88-fruix-system-fruix-freebsd`
+- validated distinct materialized source stores:
+  - Git:
+    - `/frx/store/c9928605fa906b90a600dafeebe5005dd18ad3b8e62b7111d9d13ad60ee56490-freebsd-source-stable15-side-a`
+  - `src.txz`:
+    - `/frx/store/5eaeff5c6c55a95b6531d9cf2e1824cd4368d81c614608426bee1a5d2a664dc5-freebsd-source-release15-side-b`
+- validated distinct native base outputs for the **same** version label:
+  - `15.0-source-side-by-side`
+- validated effective source roots:
+  - Git:
+    - `.../tree`
+  - `src.txz`:
+    - `.../tree/usr/src`
+
+Current assessment:
+
+- Phase 17.1 is complete
+- Fruix can now keep at least two distinct FreeBSD source revisions side by side in `/frx/store` as meaningful native base inputs/outputs
+- the next step is Phase 17.2:
+  - boot systems built from at least two distinct declared source revisions and confirm that the booted metadata tracks those revisions
+
 ## 2026-04-03 — Phase 16.3 completed: native FreeBSD base builds now consume materialized source inputs
 
 Completed work: