forth: String word set COMPARE/SEARCH/SLITERAL (+9)

plans/forth-on-sx.md

@@ -94,7 +94,7 @@ Representation:
 - [x] Source/state: `EVALUATE`, `STATE`, `[`, `]` (`SOURCE`/`>IN` stubbed; tokenized input means the exact byte/offset semantics aren't useful here)
 - [x] Misc Core: `WITHIN`, `MAX`/`MIN` (already), `ABORT`, `ABORT"`, `EXIT`, `UNLOOP`
 - [x] File Access word set (in-memory — `read-file` is not reachable from the epoch eval env)
-- [ ] String word set (`SLITERAL`, `COMPARE`, `SEARCH`)
+- [x] String word set (`SLITERAL`, `COMPARE`, `SEARCH`)
 - [ ] Target: 100% Hayes Core
 
 ### Phase 6 — speed
@@ -106,6 +106,17 @@ Representation:
 
 _Newest first._
 
+- **Phase 5 — String word set `COMPARE`/`SEARCH`/`SLITERAL` (+9).**
+  `COMPARE` walks bytes via the new `forth-compare-bytes-loop`,
+  returning -1/0/1 with standard prefix semantics (shorter string
+  compares less than its extension). `SEARCH` scans the haystack
+  with a helper `forth-search-bytes` and `forth-match-at`, returning
+  the tail after the first match or the original string with flag=0.
+  Empty needle returns at offset 0 with flag=-1 per ANS. `SLITERAL`
+  is IMMEDIATE: pops `(c-addr u)` at compile time, copies the bytes
+  into a fresh allocation, and emits the two pushes so the compiled
+  word yields the interned string at runtime.
+
 - **Phase 5 — File Access word set (in-memory backing; +4).**
   `OPEN-FILE`/`CREATE-FILE`/`CLOSE-FILE`/`READ-FILE`/`WRITE-FILE`/
   `FILE-POSITION`/`FILE-SIZE`/`REPOSITION-FILE`/`DELETE-FILE` plus