Phase V.6 → V.8b: self-hosting bytecode bootstrap reaches fixpoint

Six progressive milestones bringing OMC to a closed self-hosting loop at
the bytecode level:

  V.6  — examples/self_hosting_bytecode.omc
         AST → textual bytecode encoder + stack-VM executor in OMC.
         Integer arithmetic, while, if/else. Discovered OMC's
         pass-by-value array semantics; encoder uses return-and-rebind
         with relative jumps so concatenation needs no patch pass.

  V.7  — examples/self_hosting_v7.omc
         Function definitions, CALL/RETURN, call frames + scope stacks
         in the OMC executor. Headline: fib(10) → 55 via 177 recursive
         CALL/RETURN cycles, all on OMC-written infrastructure.

  V.7b — examples/self_hosting_v7b.omc
         LOAD_STR, MAKE_ARR, CALL_BUILTIN. Strings, array literals,
         read-only host primitives (arr_get/arr_len/str_*/concat_many)
         dispatched through a single switch. 7/7 tests pass.

  V.7c — examples/self_hosting_v7c.omc
         ARR_PUSH_NAMED, ARR_SET_NAMED — mutating array builtins via
         named-store opcodes. Test 7/8 contrast (rebind vs discard the
         return value) shows pass-by-value semantics are byte-faithful
         to tree-walk. Bytecode VM now structurally supports every
         construct the V.7b compiler uses.

  V.8  — examples/self_hosting_v8.omc
         Round-trip fixpoint driver. The same OMC code, evaluated two
         ways (tree-walk vs lex/parse/encode/execute on bytecode VM),
         returns byte-identical arrays. execute() now surfaces a
         return value via the __result scope binding. concat_many fixed
         to use to_string per arg (Display, not Debug) — closes the
         V.7b cosmetic divergence. Two demos: embedded_program and
         build_pyramid. Both ✓ FIXPOINT.

  V.8b — examples/self_hosting_v8b.omc
         # line comments, `-> type` annotations, and `break` round-trip
         identically. classify_word exercises all three. tokenize_subset
         (a real lexer, 186 bytecode ops) round-trips byte-identical to
         tree-walk — gen2 == gen3 for a compiler component. The bootstrap
         loop is architecturally closed at the feature-surface level.

A side-quest finding: OMC's str_len returns BYTE count while str_slice
is char-indexed. Hand-written lexers over non-ASCII source overshoot.
Worked around with ASCII-only embedded source; logged for V.9.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: RandomCoder-lab