Add live x86/x64 disassembly and parser-error reporting to the API by praydog · Pull Request #33 · cursey/regenny

praydog · 2026-06-03T05:29:44Z

Disassembly (Zydis):

New GET /api/memory/disassemble endpoint and regenny_disassemble MCP tool. Reads target memory and decodes Intel-syntax instructions, with a compact string mode and a detailed JSON mode (bytes/mnemonic).
New [[code]] metadata tag on Variable and Pointer nodes renders inline disassembly of the pointed-to code in the memory view.
Process::is_64_bit() picks the decoder machine mode/stack width; the Windows override uses IsWow64Process so 32-bit targets decode correctly.
Zydis v4.0.0 pulled in via CPM and linked into regenny.

Parser status reporting:

ReGenny tracks m_last_parse_error and an atomic m_parse_generation, bumped on every parse attempt so callers can detect completion.
/api/genny/content and /api/genny/reload now request a reparse and block until it finishes, returning status ok|error|pending plus the parser diagnostic instead of a silent "ok". New /api/genny/parse_error endpoint and regenny_parse_status tool expose status without reparsing.

Fixes:

serialize_struct: parents are laid out at base_offset while a struct's own variables already carry absolute in-struct offsets; the old code folded parent sizes into base_offset, double-counting derived fields.
Lua print override now forwards all arguments (variadic, tab-separated) instead of dropping everything after the first value.
Expose Process ok() and is_64_bit() to the Lua process binding.

Docs/build:

AGENT.md documents disassembly, the [[code]] tag, and @N (absolute) vs +N (relative) field-offset operators.
POST_BUILD copies AGENT.md next to the executable so /api/help resolves.

@n

Disassembly (Zydis): - New GET /api/memory/disassemble endpoint and regenny_disassemble MCP tool. Reads target memory and decodes Intel-syntax instructions, with a compact string mode and a detailed JSON mode (bytes/mnemonic). - New [[code]] metadata tag on Variable and Pointer nodes renders inline disassembly of the pointed-to code in the memory view. - Process::is_64_bit() picks the decoder machine mode/stack width; the Windows override uses IsWow64Process so 32-bit targets decode correctly. - Zydis v4.0.0 pulled in via CPM and linked into regenny. Parser status reporting: - ReGenny tracks m_last_parse_error and an atomic m_parse_generation, bumped on every parse attempt so callers can detect completion. - /api/genny/content and /api/genny/reload now request a reparse and block until it finishes, returning status ok|error|pending plus the parser diagnostic instead of a silent "ok". New /api/genny/parse_error endpoint and regenny_parse_status tool expose status without reparsing. Fixes: - serialize_struct: parents are laid out at base_offset while a struct's own variables already carry absolute in-struct offsets; the old code folded parent sizes into base_offset, double-counting derived fields. - Lua print override now forwards all arguments (variadic, tab-separated) instead of dropping everything after the first value. - Expose Process ok() and is_64_bit() to the Lua process binding. Docs/build: - AGENT.md documents disassembly, the [[code]] tag, and @n (absolute) vs +N (relative) field-offset operators. - POST_BUILD copies AGENT.md next to the executable so /api/help resolves.

Copilot

Pull request overview

This PR extends ReGenny’s embedded HTTP API + MCP toolset with (1) live x86/x64 disassembly backed by Zydis and (2) explicit parser-status/error reporting for .genny reparses, while also fixing a struct serialization offset bug and improving a few UX/binding behaviors.

Changes:

Add Zydis as a third-party dependency and introduce a new /api/memory/disassemble endpoint plus regenny_disassemble MCP tool.
Track and expose parse status via m_last_parse_error + m_parse_generation, update /api/genny/content and /api/genny/reload to wait for completion, and add /api/genny/parse_error + regenny_parse_status.
Add [[code]] metadata rendering in UI nodes (Variable/Pointer) to show inline disassembly of the pointed-to code.

Reviewed changes

Copilot reviewed 14 out of 17 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
`third_party/CMakeLists.txt`	Adds Zydis dependency via CPM.
`CMakeLists.txt`	Links Zydis and copies `AGENT.md` next to the built executable for `/api/help`.
`src/ReGenny.hpp`	Adds parse status state (`m_last_parse_error`, `m_parse_generation`) and accessors.
`src/ReGenny.cpp`	Implements parse error capture/generation bump; improves Lua `print` forwarding; exposes new Lua bindings (`ok`, `is_64_bit`).
`src/Process.hpp`	Adds `Process::is_64_bit()` virtual for decoder selection and bindings.
`src/arch/Windows.hpp` / `src/arch/Windows.cpp`	Implements Windows-specific bitness detection via `IsWow64Process`.
`src/Api.cpp`	Adds `/api/memory/disassemble`; adds parse reparse-and-wait logic and `/api/genny/parse_error`; fixes `serialize_struct` parent/derived offset handling.
`src/node/Variable.cpp`	Adds `[[code]]` metadata handling to render Zydis disassembly in the value string.
`src/node/Pointer.cpp`	Adds `[[code]]` metadata handling to render Zydis disassembly for pointer nodes.
`mcp-server/Tools.cs`	Adds `regenny_disassemble` + `regenny_parse_status` tools and updates docs for reparse status semantics.
`AGENT.md`	Documents disassembly tooling, `[[code]]`, and clarifies `@N` (absolute) vs `+N` (relative) offset operators.
`src/Project.hpp` / `src/Project.cpp`	Formatting-only changes around tab serialization.
`src/node/Undefined.cpp`	Formatting-only changes.
`src/Main.cpp`	Formatting-only changes.
`src/LoggerUi.hpp`	Formatting-only changes.

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The previous commit mixed cosmetic clang-format reformatting into the disassembly feature. This reverts the whitespace-only changes (brace expansion, line wrapping, trailing-space trimming) on lines unrelated to the feature, leaving the meaningful changes intact. Behavior is unchanged: the diff against the previous commit is empty under `git diff -w`. Five files (LoggerUi.hpp, Main.cpp, Project.cpp, Project.hpp, node/Undefined.cpp) were pure formatting and are fully restored.

The [[code]] disassembly path uses std::array<uint8_t, 300> but the file only got <array> transitively. Variable.cpp already includes it directly; match that so the include doesn't depend on header ordering. Addresses a PR review comment. The accompanying suggestion to switch the typed pointer reads to memcpy was intentionally not taken — see PR replies.

praydog · 2026-06-03T05:56:35Z

Thanks for the review. Disposition of the three comments (changes in 6e050f7, on top of 93ec95a):

Pointer.cpp missing <array> — fixed. Added the explicit #include <array> (it was only arriving transitively; Variable.cpp already includes it directly).
Use memcpy instead of typed pointer casts (Pointer.cpp) — not changed. The *(uintptr_t*)mem read is identical to two pre-existing reads in the same function, and the whole node layer uses typed casts on std::byte*. The mixed-bitness concern is a pre-existing node-layer assumption, and aliasing/alignment only matters off x86/x64 (the only thing Zydis decodes here).
Use memcpy instead of typed pointer casts (Variable.cpp) — not changed. Same consistency reason; and this path already handles pointer width via its m_size switch (4 → uint32_t, 8 → uint64_t), so the 32-bit case is already correct.

Per-thread replies inline. If you'd prefer the node layer to be strict-aliasing-clean, that's worth a separate file-wide pass rather than touching only the new lines.

Unrelated: an earlier follow-up commit 02f6d09 strips the clang-format whitespace churn that slipped into the first commit, so the feature diff is now clean.

Copilot

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Two issues from PR review: is_64_bit(): IsWow64Process() reports FALSE both for a native 64-bit process and for a 32-bit process on 32-bit Windows, so the old code reported 64-bit for every target on a 32-bit OS (wrong Zydis decoder mode). Check the OS architecture via GetNativeSystemInfo() first; only then does WOW64==FALSE reliably mean a native 64-bit target. request_reparse_and_wait(): it waited on parse_generation(), which bumps on ANY parse_file() call -- including the 1s mtime auto-reload and other UI-driven parses. An unrelated parse could satisfy the wait early, leave m_reparse_requested set (spurious extra parse next frame), and report a stale last_parse_error(). Replace it with an Api-owned completion counter (m_reparse_completed) that ReGenny::update() bumps only after consuming the API's reparse request and finishing parse_file(), so the caller observes the result of its own reparse. parse_generation() is now unused and removed (along with the <atomic> include it required).

praydog · 2026-06-03T06:13:21Z

Second review round addressed in 8186431 — both accepted:

is_64_bit() wrong on 32-bit Windows — IsWow64Process() reports FALSE for a native 64-bit process and a 32-bit process on a 32-bit OS. Now I check OS bitness via GetNativeSystemInfo() first, so WOW64==FALSE only means "native 64-bit" on a 64-bit OS.
request_reparse_and_wait() racing unrelated parses — it waited on parse_generation(), which bumps on any parse (incl. the 1s mtime auto-reload). Now it waits on an Api-owned completion counter that ReGenny::update() bumps only after consuming the API's own reparse request, so the caller observes the result of its parse. The now-unused parse_generation() was removed.

Good catches, thanks.

A process's bitness is fixed for its lifetime, but is_64_bit() ran GetNativeSystemInfo + IsWow64Process on every call, and the disassembly paths invoke it repeatedly. Compute it once in the constructor (after OpenProcess succeeds) and store it in m_is_64_bit; is_64_bit() is now a plain accessor. The member defaults to sizeof(void*) == 8, preserving the old fallback when OpenProcess fails (the ctor returns before detection).

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 7 comments.

+    auto request_reparse_and_wait = [this, rg]() -> std::pair<bool, std::string> {
+        const auto completed_before = m_reparse_completed.load();
+        m_reparse_requested.store(true);
+
+        // Poll for up to ~3s for the main thread to consume the request and finish parsing.
+        for (int i = 0; i < 300; ++i) {
+            if (m_reparse_completed.load() != completed_before) {
+                std::shared_lock lk{rg->state_mtx()};
+                return {true, rg->last_parse_error()};
+            }
+            std::this_thread::sleep_for(std::chrono::milliseconds(10));
+        }
+
+        std::shared_lock lk{rg->state_mtx()};
+        return {false, rg->last_parse_error()};
+    };


+            char formatted_insn[256];
+            ZydisFormatterFormatInstruction(&formatter, &insn, operands, insn.operand_count_visible, formatted_insn,
+                sizeof(formatted_insn), addr + offset, ZYAN_NULL);
+


+                uintptr_t code_addr = 0;
+                if (m_size == 4) {
+                    code_addr = *(uint32_t*)mem;
+                } else if (m_size == 8) {
+                    code_addr = *(uint64_t*)mem;
+                } else {
+                    code_addr = *(uintptr_t*)mem;
+                }


+                                    char formatted_insn[256];
+                                    ZydisFormatterFormatInstruction(&formatter, &insn, operands,
+                                        insn.operand_count_visible, formatted_insn, sizeof(formatted_insn),
+                                        code_addr + offset, ZYAN_NULL);
+


+                                }
+                            }
+                        }


+                                char formatted_insn[256];
+                                ZydisFormatterFormatInstruction(&formatter, &insn, operands, insn.operand_count_visible,
+                                    formatted_insn, sizeof(formatted_insn), code_addr + offset, ZYAN_NULL);
+


+                            } else {
+                                m_value_str += fmt::format("-> instruction decode failed @ 0x{:X} ", code_addr);
+                            }
+                        }
+                    }


praydog requested a review from Copilot June 3, 2026 05:30

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Add live x86/x64 disassembly and parser-error reporting to the API#33

Add live x86/x64 disassembly and parser-error reporting to the API#33
praydog wants to merge 5 commits into
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praydog commented Jun 3, 2026 •

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praydog commented Jun 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Disassembly (Zydis):

Parser status reporting:

Fixes:

Docs/build:

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praydog commented Jun 3, 2026 •

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