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feat(abi): implement binary ABI + Zig↔Idris layout cross-check
Close the open HIGH proof item (Zig↔Idris layout cross-check) and make the previously-aspirational binary ABI real. Layout.idr's proofs show the layout *model* is internally consistent, but nothing checked those hand-written offsets against the C layout Zig actually emits, and the offset-reader FFI that GSA.ABI.Foreign binds was unimplemented (9 dead bindings; no extern structs anywhere). - abi_layout.zig: declare the 8 ABI structs as Zig `extern struct`s and assert at comptime (+ `zig build test`) that @offsetOf/@sizeOf/@Alignof of every field equal the proven Layout.idr constants. A divergence is a compile error (negative-tested). - scripts/gen_abi_expected.py: lift the constants from Layout.idr (single source of truth) into the generated abi_layout_expected.zig used by the check. - abi_serde.zig: implement the readers/helpers Foreign.idr binds — read_int/read_double/read_ptr/read_string, array_len/array_get_string, is_null/free, apply_config/close_handle — plus emitters and an exported gossamer_gsa_drift_struct producer. Round-trip tests read each field back at its proven Layout.idr offset, making the offsets a live runtime contract. - Foreign.idr: getDrift now decodes a DriftReport at offsetOf-derived offsets (was wrong hand-tuned 0/4/12/20/28) via prim__driftStruct + read_ptr/read_int/ read_double; adds prim__readPtr / prim__driftStruct bindings. Verified: zig build + test/integration/smoke (124 tests) green on Zig 0.15.2; idris2 0.7.0 typechecks the ABI. Exported FFI symbols 27 -> 38. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LvsZgNxFbeqfRmrVFNhJ8G
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Lines changed: 879 additions & 23 deletions

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‎.claude/CLAUDE.md‎

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@@ -41,7 +41,7 @@ panic-attack assail .
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```
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Gossamer GUI (Ephapax .eph) -- src/core/, src/gui/panels/
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| IPC (gossamer:// protocol)
44-
Zig FFI (libgsa.so + gsa CLI) -- src/interface/ffi/src/ (9 modules)
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Zig FFI (libgsa.so + gsa CLI) -- src/interface/ffi/src/ (11 modules)
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| C ABI (13 result codes)
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Idris2 ABI (Types/Foreign/Layout) -- src/interface/abi/
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| REST (port 8090)
@@ -60,8 +60,13 @@ VeriSimDB (8-modality octads) -- container/verisimdb/
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| `server_actions.zig` | Start/stop/restart/logs via Podman/Docker/systemd |
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| `game_profiles.zig` | A2ML profile registry + parser |
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| `groove_client.zig` | .well-known Groove voice alerting |
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| `abi_layout.zig` | Canonical C-ABI `extern struct`s + comptime Zig↔Idris layout cross-check |
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| `abi_serde.zig` | Binary ABI emitters + offset readers (`read_int`/`read_ptr`/…) — makes `Layout.idr` offsets a live contract |
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| `cli.zig` | Standalone CLI executable (status, probe, profiles, version) |
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`abi_layout_expected.zig` is generated from `Layout.idr` by
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`scripts/gen_abi_expected.py` (regenerate when `Layout.idr` changes).
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## Key Conventions
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- **All exported FFI functions** are prefixed `gossamer_gsa_` and use `pub export fn ... callconv(.c)`
@@ -78,13 +83,15 @@ VeriSimDB (8-modality octads) -- container/verisimdb/
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- **Completion**: 93% (15 phases built; v1.0.0 gates still open — see Remaining)
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- **Zig version**: 0.15.2 (see `.tool-versions`)
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- **Exported FFI symbols**: 27 (comptime linker hints in main.zig)
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- **Tests**: 111 Zig tests across 3 suites (unit: 67, integration: 39, smoke: 5). All passing.
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- **Exported FFI symbols**: 38 (comptime linker hints in main.zig)
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- **Tests**: 124 Zig tests across 3 suites (unit: 80, integration: 39, smoke: 5). All passing.
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- Security tests for command injection in server_actions
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- Config parser edge cases for all 8 formats
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- A2ML round-trip, diff, and secret redaction tests
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- Groove target registry overflow and buffer truncation tests
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- ABI layout cross-check + binary ABI round-trip (read at proven `Layout.idr` offsets)
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- **Idris2 ABI**: Alignment postulate replaced with constructive proof (`alignUpCeil` + `alignUpCeilIsMultiple`)
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- **Cross-language ABI**: `abi_layout.zig` asserts (at compile time + `zig build test`) that the 8 `extern struct`s match the proven `Layout.idr` offsets/sizes; `abi_serde.zig` implements the offset readers/emitters so those offsets are a live runtime contract (was the open HIGH proof item)
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- **VeriSimDB**: Main on 8090 (built, running), backup on 8091 (game saves)
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- **Container**: Containerfile wired with real Zig build, entrypoint.sh execs gsa
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- **Nix/Guix**: Both flake.nix and guix.scm have real build/install phases

‎PROOF-NEEDS.md‎

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@@ -1,9 +1,11 @@
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# Proof Requirements
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## Current State (2026-06-21 — verified with Idris2 0.7.0)
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## Current State (2026-06-21 — verified with Idris2 0.7.0 + Zig 0.15.2)
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The ABI package typechecks end-to-end (all modules `%default total`, no
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`postulate` / `believe_me` / `assert_total`):
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`postulate` / `believe_me` / `assert_total`), and the hand-written Idris layout
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constants are now cross-checked against the real C layout the Zig compiler emits
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(see *Cross-language ABI* below):
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```bash
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cd src/interface/abi && idris2 --typecheck gsa-abi.ipkg
@@ -54,13 +56,36 @@ Decidable `portInRange`, `nonEmptyId`, `configFieldCountPositive`,
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`allPortsValid`, the `Valid*` smart constructors, and the linear
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`ServerHandle` with its erased non-null witness.
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### Cross-language ABI (`abi_layout.zig` / `abi_serde.zig`)
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The Idris proofs above show the *model* is internally consistent; the Zig side
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now checks that model against reality and makes it a live runtime contract.
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- **Layout cross-check (was the open HIGH item).** Each of the 8 structs is
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declared as a Zig `extern struct` (`abi_layout.zig`). A comptime block asserts
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`@offsetOf` / `@sizeOf` / `@alignOf` of every field equals the proven Idris
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constant — lifted verbatim from `Layout.idr` into `abi_layout_expected.zig` by
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`scripts/gen_abi_expected.py`. Any divergence is a **compile error**, so the
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library cannot build against a layout the proofs do not describe. A negative
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test (perturbing one offset) confirms the guard bites; the check also runs
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under `zig build test`.
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- **Live offset contract.** The previously-unimplemented FFI readers that
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`GSA.ABI.Foreign` binds are now real (`abi_serde.zig`): `read_int` /
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`read_double` / `read_ptr` decode fields at a byte offset; `read_string`,
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`array_len`, `array_get_string`, `is_null`, `free` handle strings/arrays;
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`apply_config` / `close_handle` round out the surface. Emitters
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(`serializeDriftReport` / `serializeFingerprint` / `serializeStringArray`)
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write the wire structs, and `gossamer_gsa_drift_struct` exports one. Round-trip
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tests read each field back at its **proven** `Layout.idr` offset, standing in
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for the Idris reader — so agreement is an end-to-end cross-language guarantee.
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- **Idris consumer.** `Foreign.getDrift` now decodes a `DriftReport` at offsets
81+
taken from `offsetOf … driftReportLayout` (not the previous, wrong hand-tuned
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`0/4/12/20/28`), via `prim__driftStruct` + `prim__readPtr`/`readInt`/`readDouble`.
83+
84+
> Regenerate the expected table whenever `Layout.idr` changes:
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> `python3 scripts/gen_abi_expected.py` (then the Zig cross-check re-validates).
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## What still needs proving
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- **Zig ↔ Idris layout cross-check (HIGH).** `Layout.idr` proves the Idris
60-
model is internally consistent, but nothing yet checks the hand-written
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field offsets/sizes against Zig's `@sizeOf`/`@offsetOf`. A generated test
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emitting Zig's numbers and comparing them to the `Layout` constants would
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close the actual cross-language ABI guarantee.
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- **Server probe safety (MEDIUM).** Prove probes cause no side effects on
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targets. Needs a specification first.
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- **Configuration drift-detection completeness (LOW).** Needs a richer spec.

‎scripts/gen_abi_expected.py‎

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#!/usr/bin/env python3
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# SPDX-License-Identifier: AGPL-3.0-or-later
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# Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
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#
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# gen_abi_expected.py — extract the canonical C-ABI layout numbers from the
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# machine-checked Idris2 model (src/interface/abi/Layout.idr) and emit a Zig
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# source file (src/interface/ffi/src/abi_layout_expected.zig) consumed by the
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# Zig-side cross-check (abi_layout.zig).
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#
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# Layout.idr is the single source of truth: it carries the proofs (NoOverlap,
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# AllFieldsAligned, SizeAligned, SizeCoversFields). This script lifts the same
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# `MkFieldDesc name offset size align` / `MkStructLayout [...] total align`
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# constants into Zig so the compiler can assert `@offsetOf`/`@sizeOf`/`@alignOf`
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# of the canonical extern structs agree with the proven model.
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#
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# Run from the repository root:
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# python3 scripts/gen_abi_expected.py
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# The build/CI re-runs this and `git diff --exit-code`s the result to guarantee
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# the Zig expectations never drift from the Idris proofs.
20+
21+
import re
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import sys
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import pathlib
24+
25+
# Idris layout variable (lowerCamel, without the "Layout" suffix) -> Zig struct
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# type name. Drives both extraction and the emitted const names.
27+
STRUCTS = {
28+
"serverHandle": "ServerHandle",
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"probeResult": "ProbeResult",
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"configField": "ConfigField",
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"a2mlConfig": "A2MLConfig",
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"gameProfile": "GameProfile",
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"serverOctad": "ServerOctad",
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"fingerprint": "Fingerprint",
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"driftReport": "DriftReport",
36+
}
37+
38+
FIELD_RE = re.compile(
39+
r'MkFieldDesc\s+"(?P<name>\w+)"\s+(?P<offset>\d+)\s+(?P<size>\d+)\s+(?P<align>\d+)'
40+
)
41+
42+
43+
def parse_layout(text, var):
44+
"""Return (fields, total_size, struct_align) for `<var>Layout`."""
45+
# Match: <var>Layout = MkStructLayout [ ...fields... ] <total> <align>
46+
block_re = re.compile(
47+
r'\b' + re.escape(var) + r'Layout\s*=\s*MkStructLayout\s*\[(?P<body>.*?)\]\s*'
48+
r'(?P<total>\d+)\s+(?P<align>\d+)',
49+
re.DOTALL,
50+
)
51+
m = block_re.search(text)
52+
if not m:
53+
raise SystemExit(f"error: could not find {var}Layout in Layout.idr")
54+
fields = []
55+
for fm in FIELD_RE.finditer(m.group("body")):
56+
name = fm.group("name")
57+
if name.startswith("padding"):
58+
continue # implicit C padding; not a real extern-struct field
59+
fields.append(
60+
(name, int(fm.group("offset")), int(fm.group("size")), int(fm.group("align")))
61+
)
62+
return fields, int(m.group("total")), int(m.group("align"))
63+
64+
65+
def main():
66+
root = pathlib.Path(__file__).resolve().parent.parent
67+
layout_idr = root / "src" / "interface" / "abi" / "Layout.idr"
68+
out_zig = root / "src" / "interface" / "ffi" / "src" / "abi_layout_expected.zig"
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70+
text = layout_idr.read_text(encoding="utf-8")
71+
72+
out = []
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out.append("// SPDX-License-Identifier: AGPL-3.0-or-later")
74+
out.append("// Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>")
75+
out.append("//")
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out.append("// @generated by scripts/gen_abi_expected.py from src/interface/abi/Layout.idr")
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out.append("// DO NOT EDIT. Regenerate with: python3 scripts/gen_abi_expected.py")
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out.append("//")
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out.append("// Canonical C-ABI layout numbers lifted from the machine-checked Idris2 model")
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out.append("// (GSA.ABI.Layout). Consumed by abi_layout.zig to assert that the Zig extern")
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out.append("// structs agree, byte-for-byte, with the proven Idris layout.")
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out.append("")
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out.append("pub const Field = struct {")
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out.append(" name: []const u8,")
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out.append(" offset: u32,")
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out.append(" size: u32,")
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out.append(" alignment: u32,")
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out.append("};")
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out.append("")
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out.append("pub const StructExpect = struct {")
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out.append(" name: []const u8,")
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out.append(" total_size: u32,")
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out.append(" struct_align: u32,")
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out.append(" fields: []const Field,")
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out.append("};")
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out.append("")
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names = []
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for var, zig_name in STRUCTS.items():
100+
fields, total, align = parse_layout(text, var)
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names.append(zig_name)
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out.append(f"pub const {zig_name} = StructExpect{{")
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out.append(f' .name = "{zig_name}",')
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out.append(f" .total_size = {total},")
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out.append(f" .struct_align = {align},")
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out.append(" .fields = &.{")
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for (fn, off, sz, al) in fields:
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out.append(
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f' .{{ .name = "{fn}", .offset = {off}, .size = {sz}, .alignment = {al} }},'
110+
)
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out.append(" },")
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out.append("};")
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out.append("")
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out.append("pub const all = [_]StructExpect{ " + ", ".join(names) + " };")
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out.append("")
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out_zig.write_text("\n".join(out), encoding="utf-8")
119+
print(f"wrote {out_zig.relative_to(root)} ({len(names)} structs)")
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if __name__ == "__main__":
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sys.exit(main())

‎src/interface/abi/Foreign.idr‎

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@@ -192,6 +192,23 @@ export
192192
%foreign "C:gossamer_gsa_array_get_string, libgossamer_gsa"
193193
prim__arrayGetString : AnyPtr -> Int -> PrimIO String
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195+
||| Read a pointer field at a byte offset from a serialised struct. Combined
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||| with prim__readString this decodes char* fields at their proven offsets:
197+
||| readString (readPtr struct (offsetOf "serverId" layout)).
198+
|||
199+
||| C signature: void* gossamer_gsa_read_ptr(void* ptr, int32_t offset)
200+
export
201+
%foreign "C:gossamer_gsa_read_ptr, libgossamer_gsa"
202+
prim__readPtr : AnyPtr -> Int -> PrimIO AnyPtr
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204+
||| Emit a binary DriftReport wire struct (canonical Layout.idr layout) for a
205+
||| tracked server. The returned pointer must be released with prim__free.
206+
|||
207+
||| C signature: void* gossamer_gsa_drift_struct(const char* server_id)
208+
export
209+
%foreign "C:gossamer_gsa_drift_struct, libgossamer_gsa"
210+
prim__driftStruct : String -> PrimIO AnyPtr
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195212
--------------------------------------------------------------------------------
196213
-- Internal Helpers
197214
-- Utility functions used by the safe wrappers to convert between C
@@ -457,30 +474,40 @@ checkHealth = do
457474
Just status => pure (Right status)
458475
Nothing => pure (Left Error)
459476

460-
||| Get a drift report for a specific server.
461-
||| Compares the server's current VeriSimDB octad against its historical
462-
||| baseline across all modalities (config, semantic, temporal).
477+
||| Get a drift report for a specific server, decoded from the binary
478+
||| DriftReport wire struct emitted by gossamer_gsa_drift_struct.
479+
|||
480+
||| Every field is read at the offset *proven* in GSA.ABI.Layout
481+
||| (driftReportLayout): the char* field serverId via prim__readPtr, the scalars
482+
||| via prim__readInt / prim__readDouble. These are the same offsets the Zig
483+
||| layer is compile-time-checked against (abi_layout.zig), so this is the live
484+
||| cross-language ABI contract rather than hand-tuned constants.
485+
|||
486+
||| status reflects the tracked liveness; the configDrift / semanticDrift /
487+
||| temporalConsistency / overallScore metrics are 0.0 until VeriSimDB scoring
488+
||| is wired into the emitter.
463489
|||
464490
||| @param serverId The server identifier to check
465491
||| @return Left Result on failure, Right DriftReport on success
466492
export
467493
covering
468494
getDrift : String -> IO (Either Result DriftReport)
469495
getDrift serverId = do
470-
ptr <- primIO (prim__verisimdbDrift serverId)
496+
ptr <- primIO (prim__driftStruct serverId)
471497
case prim__isNull ptr /= 0 of
472-
True => pure (Left VeriSimDBUnavailable)
498+
True => pure (Left Error)
473499
False => do
474-
-- Deserialise the DriftReport from the returned pointer.
475-
-- Field offsets match the Zig struct layout (see Layout.idr).
476-
statusCode <- primIO (prim__readInt ptr 0)
477-
configDrift <- primIO (prim__readDouble ptr 4)
478-
semanticDrift <- primIO (prim__readDouble ptr 12)
479-
temporalCons <- primIO (prim__readDouble ptr 20)
480-
overallScore <- primIO (prim__readDouble ptr 28)
500+
let o = \name => the Int (cast (fromMaybe 0 (Layout.offsetOf name Layout.driftReportLayout)))
501+
sidPtr <- primIO (prim__readPtr ptr (o "serverId"))
502+
sid <- primIO (prim__readString sidPtr)
503+
statusCode <- primIO (prim__readInt ptr (o "status"))
504+
configDrift <- primIO (prim__readDouble ptr (o "configDrift"))
505+
semanticDrift <- primIO (prim__readDouble ptr (o "semanticDrift"))
506+
temporalCons <- primIO (prim__readDouble ptr (o "temporalConsistency"))
507+
overallScore <- primIO (prim__readDouble ptr (o "overallScore"))
481508
primIO (prim__free ptr)
482509
let status = fromMaybe Warning (healthStatusFromInt statusCode)
483-
pure (Right (MkDriftReport serverId status configDrift semanticDrift temporalCons overallScore))
510+
pure (Right (MkDriftReport sid status configDrift semanticDrift temporalCons overallScore))
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485512
--------------------------------------------------------------------------------
486513
-- Safe Wrappers: Profile Management

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