docs: refresh Phase-C TODO — audit results + remaining edge cases

Update the 1.0-readiness document with:
- 2026-04-18 compatibility audit results: 50/47 build rate (94%)
  vs previous 40/34. Lists every fix commit this session.
- Four remaining low-priority edge cases from the audit (xcommand
  nested-comma args, u64 overflow, USE with ../ paths, legacy
  inline-C syntax) — none block a realistic 1.0.
- Revised Phase-C scope: user clarified contrib PRGs can be
  imported as-is so long as underlying RTL exists, so the work is
  "audit each contrib's low-level deps, fill gaps, copy .prg"
  rather than porting every function.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/Five-1.0-Phase-C-TODO.md

@@ -1,10 +1,15 @@
 # Five 1.0 — Phase C TODO (Harbour Contrib Libraries)
 
-Status as of commit `2a66252` (2026-04-18).
+Status as of commit `4a1bbdb` (2026-04-18).
 
 ## Context
 
-Phase A (language blockers) and Phase B (RTL blockers) are complete:
+Phase A (language blockers), Phase B (RTL blockers), and the
+compatibility-audit follow-ups are complete. Summary below, then the
+remaining Phase C work (contrib libraries) + a short list of
+low-priority edge cases surfaced by the Harbour test-suite audit.
+
+### Phase A — language blockers (done)
 
 - `::super:Method()` dispatch — `3a56bd3`
 - `METHOD INLINE` + `MESSAGE INLINE` — `34485cd`
@@ -12,12 +17,53 @@ Phase A (language blockers) and Phase B (RTL blockers) are complete:
 - `&var` / `&(expr)` runtime macro — `e089c81`
 - `DATA x, y, z` multi-name parse — `327f75b`
 - `DO(xTarget, args...)` — `2a66252`
-- ACCEPT — skipped (user decision, revisit if needed)
-- 11 `HBTYPE` functions — **not actually blockers**: these are Harbour's
-  scalar class factories (`HBARRAY` etc. wrap the Array class used for
-  `cStr:Upper()` syntax). Five provides the same surface via
-  `hbrt/valuemethods.go` `SendBuiltin` and doesn't need the C-level
-  factories exposed.
+
+### Phase B — RTL blockers (done / re-scoped)
+
+- ACCEPT — user deferred (revisit if needed).
+- 11 `HBTYPE` functions — **not actually blockers**: these are
+  Harbour's scalar class factories (`HBARRAY` wraps the Array
+  scalar class used for `cStr:Upper()` syntax). Five provides the
+  same surface via `hbrt/valuemethods.go` `SendBuiltin` and doesn't
+  need the C-level factories exposed.
+
+### 2026-04-18 audit follow-ups (done)
+
+Harbour test suite re-audit (50 files sampled, broad coverage) moved
+from 34/40 building to 47/50 (94%). Fixes landed:
+
+- Implicit CLASS binding for standalone METHOD bodies — `0a5482b`
+- Keyword-as-identifier at stmt-block boundaries — `d3c4447`
+- `common.ch` ISNIL/ISARRAY/ISNUMBER/ISCHARACTER/ISDATE/ISLOGICAL/
+  ISOBJECT/ISBLOCK/ISMEMO aliases — `d6c2610`
+- `#xcommand NAME( <m>, <n> )` paren-attached keyword — `4b629f7`
+- SWITCH empty / OTHERWISE-only / EXIT-from-case — `65b2edc`
+- `M->` / `MEMVAR->` memvar access — `385a4ec`
+- PP stringify markers + paren-balanced capture — `e952277`
+- `USE &cFile ALIAS &a INDEX &c` macro args — `85002df`
+- `#pragma BEGINDUMP` inline-C detection with friendly error — `5514780`
+- Inline Go #pragma BEGINDUMP imports hoisted + HB_FUNC dispatch — `b1024c5`
+- `#xcommand [, <vn> TO <xn>]` optional-repeat blocks (DEFAULT / UPDATE
+  in common.ch now work) — `4a1bbdb`
+
+### Remaining low-priority edge cases (from the audit)
+
+| # | Symptom | Where | Scope |
+|---|---------|-------|-------|
+| 1 | `RDDTESTF NIL, {arr}, call()` — xcommand taking a `<x>` regular marker where the argument itself contains top-level commas. PP captures fine but expansion produces output that the Harbour-style `rddtst_wr` can't re-parse. | `tests/rddtest/adscl52.prg`, `adscl53.prg` | xcommand argument-count resolution OR extend `<*x*>` wild marker support. ~2-4h |
+| 2 | Integer overflow on u64 literals like `18446744073709600000`. Five emits Go's signed int64; overflow causes `cannot use ... (untyped int constant)` in generated Go. | `tests/dyn.prg` | Route large literals to Go `uint64` / `math/big`. ~1-2h |
+| 3 | `USE ../alias` — relative path literal with `../` tokenised as decimal-dot operator. | `tests/mt/mttest10.prg` | Lexer context for `..` inside USE filename. ~1-2h |
+| 4 | Harbour legacy `identifier { C-code }` inline C block syntax (deprecated form predating `#pragma BEGINDUMP`). | `tests/hbinline.prg` | Friendly error similar to `5514780`. ~30min. |
+
+None block a realistic 1.0 — all are specialised to Harbour's own
+test conventions, not production code patterns.
+
+## Phase C scope
+
+Originally three libraries (hbct, hbnf, hbtip). User clarified: PRG
+contribs can be **imported as-is** as long as their low-level RTL
+deps exist in Five. So Phase C is really "audit each contrib's RTL
+dependencies, fill the gaps, then copy the `.prg` files wholesale".
 
 Remaining for 1.0 is the contrib library ecosystem — Harbour ships
 ~70 libraries under `harbour-core/contrib/`, only a handful of which