docs(agents): split CONVENTIONS.md into topic files under AGENTS/CONVENTIONS

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

1 files changed, 20 insertions, 0 deletions

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+# Conventions: STRING values and ownership
+
+Part of [Load-bearing conventions](../CONVENTIONS.md).
+
+**STRING values use the class machinery.** `string.cps` owns a std::string through an
+internal handle. Ordinary literals construct STRING through NEW(C_STRING); suffixed
+`"text"C` literals produce C_STRING directly. Ordinary literals retain legacy NUL
+truncation. `StringValueGen.cc` bridges construction, C_STR access and file operands;
+INPUT calls READ_INPUT. String functions and all concatenation/comparison operators
+are ordinary library definitions, with exact overload selection. Comparisons use
+case-sensitive byte ordering. A missing STRING class or required bridge method is a
+compile error.
+
+**Ownership follows value copies.** STRING constructors/assignment prevent shared
+handles. Records and BYVAL arrays containing STRING recursively copy their
+string-bearing fields/elements; RETURN and temporary cleanup preserve ownership.
+C_STRING casts borrow a STRING buffer or construct an owning STRING copy in the other
+direction. FileHandler owns copied open-file names and frees them on close; READFILE
+buffers are copied into STRING and released. Explicit MemoryHandler allocations remain
+separate from these internal objects.