name: "Tutorial: Composing Modules with the Module Context"
output: tutorial-composing-modules.md
project_name: logos-calc-aggregator-module
requires:
  - tutorial-wrapping-c-library.test.yaml
release: ""

intro: |
  This tutorial builds `calc_aggregator`, a **core module that depends on another module** (`calc_module` from [Part 1](tutorial-wrapping-c-library.md)). It does no arithmetic of its own — instead it *composes* `calc_module`'s primitives into a single call, and along the way showcases everything the SDK's `LogosModuleContext` base class gives a universal module. There is no UI: you drive the whole thing from `logoscore` on the command line.

what_you_build: |
  A `calc_aggregator` core module that, through the `LogosModuleContext` base class:

  - reads the three host-injected properties — `modulePath()`, `instanceId()`, `instancePersistencePath()`
  - persists state in its per-instance data directory (a run counter that survives restarts), wired up in the `onContextReady()` hook
  - calls `calc_module` with the generated, type-safe `modules().calc_module` wrappers — **synchronously** (five calls composed into one `computeReport`) and **asynchronously** (`fibonacciAsync` with a callback)
  - subscribes to `calc_module`'s `versionReady` **event** with a typed callback

  No Qt, no `LogosAPI`, no plugin boilerplate — one plain C++ class, exactly like Part 1.

what_you_learn:
  - How one module declares another as a dependency (`metadata.json` + `flake.nix` input)
  - How `LogosModuleContext` exposes `modulePath` / `instanceId` / `instancePersistencePath` to a universal module
  - How to use the per-instance persistence directory for durable state, set up in `onContextReady()`
  - How `modules().<dep>` gives you typed **sync** and **async** callers — no raw `LogosAPI`, no `QVariant`
  - How to subscribe to another module's `logos_events:` with a typed callback
  - How to load two modules in `logoscore` and chain calls to observe events and async replies

prerequisites:
  - "Completed [Part 1](tutorial-wrapping-c-library.md) — you have a working `calc_module` whose shared library is built (`libcalc.so`/`.dylib` in `logos-calc-module/lib/`). This tutorial only needs `calc_module`; the UI tutorials (Parts 2–3) are not required."
  - Nix with flakes enabled
  - Basic familiarity with C++

sections:
  # ── Step 1: Scaffold ────────────────────────────────────────────────────────
  - title: "Scaffold the Module Project"
    step: true
    text: |
      Create a new directory and initialise it from the minimal module template:

      `mkdir logos-calc-aggregator-module && cd logos-calc-aggregator-module`
    steps:
      - title: "Create the project from the template"
        run: "nix flake init -t github:logos-co/logos-module-builder{release}"
        code_block: |
          nix flake init -t github:logos-co/logos-module-builder{release}
        post_text: |
          This scaffolds a `flake.nix`, `metadata.json`, `CMakeLists.txt`, and a `src/` directory pre-wired for `logos-module-builder`. As in Part 1 we use the newer **pure-C++ (`interface: universal`) pattern**, so we replace the template's example `src/` files with a single plain `*_impl.h` / `*_impl.cpp` class.

      - title: "Remove the template's example sources"
        text: |
          The minimal template ships an example Qt plugin (`minimal_*`). Delete those — this tutorial supplies its own pure-C++ `src/` files:
        run: "rm -f src/minimal_interface.h src/minimal_plugin.h src/minimal_plugin.cpp"

  # ── Step 2: Configure the module ────────────────────────────────────────────
  - title: "Configure the Module"
    step: true
    text: |
      Three small config files declare the module, its dependency on `calc_module`, and how to build it.
    steps:
      - title: "`metadata.json` — declare the dependency"
        text: |
          The one field that matters here is `dependencies`: listing `calc_module` tells the builder to read `calc_module`'s published LIDL interface contract and generate a typed wrapper for it — without building `calc_module` itself. The dependency name **must match** `calc_module`'s own `metadata.json` `name`.
        file:
          path: metadata.json
          language: json
          content: |
            {
              "name": "calc_aggregator",
              "version": "1.0.0",
              "type": "core",
              "category": "general",
              "description": "Composes calc_module and showcases LogosModuleContext",
              "main": "calc_aggregator_plugin",
              "interface": "universal",
              "dependencies": ["calc_module"],

              "nix": {
                "packages": {
                  "build": [],
                  "runtime": []
                },
                "external_libraries": [],
                "cmake": {
                  "find_packages": [],
                  "extra_sources": [],
                  "extra_include_dirs": [],
                  "extra_link_libraries": []
                }
              }
            }
        post_text: |
          | Field          | What it does                                                                                                  |
          | -------------- | ------------------------------------------------------------------------------------------------------------- |
          | `interface`    | `"universal"` — you write one plain C++ class; the builder generates the Qt plugin glue                       |
          | `dependencies` | `["calc_module"]` — the builder generates `modules().calc_module`, a typed wrapper with sync/async/event APIs |

          Unlike Part 1, there is no `external_libraries` entry — this module wraps no C library, it depends on another **module**.

      - title: "`CMakeLists.txt` — list your sources"
        text: |
          For a universal module you list only your plain C++ files. The generated dependency glue is compiled automatically.
        file:
          path: CMakeLists.txt
          language: cmake
          content: |
            cmake_minimum_required(VERSION 3.14)
            project(CalcAggregatorPlugin LANGUAGES CXX)

            # Include the Logos Module CMake helper (provided by logos-module-builder)
            if(DEFINED ENV{LOGOS_MODULE_BUILDER_ROOT})
                include($ENV{LOGOS_MODULE_BUILDER_ROOT}/cmake/LogosModule.cmake)
            elseif(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/cmake/LogosModule.cmake")
                include(cmake/LogosModule.cmake)
            else()
                message(FATAL_ERROR "LogosModule.cmake not found")
            endif()

            logos_module(
                NAME calc_aggregator
                SOURCES
                    src/calc_aggregator_impl.h
                    src/calc_aggregator_impl.cpp
            )
        post_text: |
          `NAME` must match `name` in `metadata.json` (`calc_aggregator`). No `EXTERNAL_LIBS` here — the only dependency is another module, resolved via `metadata.json` + `flake.nix`, not CMake.

      - title: "`flake.nix` — add the dependency input"
        text: |
          Declare `calc_module` as a flake input. The input attribute name **must match** the dependency name in `metadata.json`. The `path:/path/to/your/calc_module` value is a placeholder — you lock it to your real Part 1 checkout in the build step with `--override-input` (Nix won't accept a relative `../` path written directly into `flake.nix`).
        file:
          path: flake.nix
          language: nix
          content: |
            {
              description = "Aggregator core module - composes calc_module and showcases LogosModuleContext";

              inputs = {
                logos-module-builder.url = "github:logos-co/logos-module-builder{release}";

                # The module this one depends on. Placeholder path — locked to your
                # real checkout in the build step via `--override-input`.
                calc_module.url = "path:/path/to/your/calc_module";
              };

              outputs = inputs@{ logos-module-builder, calc_module, ... }:
                logos-module-builder.lib.mkLogosModule {
                  src = ./.;
                  configFile = ./metadata.json;
                  flakeInputs = inputs;
                };
            }
        post_text: |
          `flakeInputs = inputs` hands every input (including `calc_module`) to the builder, which resolves the `calc_module` dependency declared in `metadata.json` and runs `logos-cpp-generator` to emit the typed wrapper.

  # ── Step 3: Write the module ────────────────────────────────────────────────
  - title: "Write the Module Class"
    step: true
    text: |
      The whole module is one plain C++ class that inherits `LogosModuleContext`. Inheriting that base is what unlocks the context getters (`modulePath()` / `instanceId()` / `instancePersistencePath()`), the `onContextReady()` hook, and `modules()` — typed access to declared dependencies. No Qt anywhere.
    steps:
      - title: "`src/calc_aggregator_impl.h` — the class"
        text: |
          Every `public` method becomes callable over IPC. The methods fall into four groups: the context getters, the persistence demo, the sync/async composition of `calc_module`, and the event subscription.
        file:
          path: src/calc_aggregator_impl.h
          language: cpp
          content: |
            #pragma once

            #include <cstdint>
            #include <string>

            #include <logos_json.h>            // LogosMap (QVariantMap on the wire)
            #include <logos_module_context.h>  // LogosModuleContext base class

            // A core module that depends on calc_module. It does no arithmetic of
            // its own — it *composes* calc_module's primitives and showcases what
            // the SDK's LogosModuleContext base class gives a universal module:
            //
            //   • modulePath()              — where the plugin was loaded from
            //   • instanceId()              — host-assigned, stable per persistence dir
            //   • instancePersistencePath() — per-instance writable data directory
            //   • onContextReady()          — one-time setup hook
            //   • modules()                 — typed access to declared dependencies
            //                                 (sync callers, async callers, events)
            //
            // Because metadata.json sets "interface": "universal", the builder
            // generates the Qt plugin wrapper from this plain class.
            class CalcAggregatorImpl : public LogosModuleContext {
            public:
                CalcAggregatorImpl() = default;
                ~CalcAggregatorImpl() = default;

                // ── The three host-injected context properties ─────────────────

                /// Directory the plugin file was loaded from (modulePath()).
                std::string moduleDir() const;

                /// Host-assigned instance ID (instanceId()).
                std::string instanceID() const;

                /// True iff the host populated a non-empty instance ID. A bool
                /// return distinguishes "host wired it" from the empty-string
                /// default a plain string getter can't tell apart over the CLI.
                bool hasInstanceID() const;

                /// Per-instance writable data directory (instancePersistencePath()).
                std::string persistenceDir() const;

                /// Increments a counter stored under persistenceDir() and returns
                /// the new value. The persistence dir is host-owned and durable, so
                /// the count keeps climbing across restarts — it is loaded back in
                /// onContextReady().
                int64_t bumpRunCount();

                // ── Compose calc_module: five sync calls into one result ───────

                /// Runs add / multiply / factorial / fibonacci / libVersion on
                /// calc_module and returns them as a single map. One call here
                /// fans out to five typed, synchronous cross-module calls.
                LogosMap computeReport(int64_t a, int64_t b, int64_t n);

                // ── Compose calc_module: an async call ─────────────────────────

                /// Fires calc_module.fibonacci(n) *asynchronously* and returns
                /// right away ("queued"). The reply lands later in a callback that
                /// stashes it; read it back with asyncResult().
                std::string startAsyncFibonacci(int64_t n);

                /// The most recent value delivered by startAsyncFibonacci()'s
                /// callback, or -1 if none has arrived yet.
                int64_t asyncResult() const;

                // ── Subscribe to a calc_module event ───────────────────────────

                /// Subscribes to calc_module's `versionReady` event with a typed
                /// callback. Returns "ok" once registered. Trigger it by calling
                /// calc_module.libVersionNotify().
                std::string subscribeVersion();

                /// The last version string delivered by the versionReady
                /// subscription, or empty until one fires.
                std::string lastVersionEvent() const;

            protected:
                // One-time hook the framework fires once the context getters above
                // are populated, before any method dispatch — the canonical place
                // for setup that needs the persistence path.
                void onContextReady() override;

            private:
                int64_t     m_runCount = 0;
                int64_t     m_asyncResult = -1;
                std::string m_lastVersionEvent;
                bool        m_subscribed = false;
            };
        post_text: |
          A few things to notice:

          - The class inherits **`LogosModuleContext`** — that's the opt-in that gives it the context getters and `modules()`.
          - `onContextReady()` is `protected` (an override of the base hook), so it is **not** exposed over IPC — only the `public` methods are.
          - `hasInstanceID()` returns `bool` on purpose: the CLI prints a `Result:` line for any string (even empty), so a boolean is the unambiguous way to assert "the host populated the ID".

      - title: "`src/calc_aggregator_impl.cpp` — the implementation"
        text: |
          The `.cpp` includes the generated `logos_sdk.h` (which defines `LogosModules`) — that's why the cross-module calls live here and not in the header the generator parses. Each group of methods maps one-to-one onto the bullets in the class comment.
        file:
          path: src/calc_aggregator_impl.cpp
          language: cpp
          content: |
            #include "calc_aggregator_impl.h"

            #include <fstream>

            // Generated at build time by logos-cpp-generator. Defines `LogosModules`
            // with one std-typed accessor per metadata.json dependency — here
            // `calc_module`. Included only in the .cpp so the impl header the
            // generator parses stays free of Qt and codegen types.
            #include "logos_sdk.h"

            namespace {
            // The run-count file lives inside the host-provisioned persistence dir.
            // An empty dir means the module was constructed outside a host (e.g. a
            // unit test) — treat that as "nothing to persist".
            std::string runCountPath(const std::string& dir) {
                return dir.empty() ? std::string() : dir + "/runcount.txt";
            }
            }  // namespace

            void CalcAggregatorImpl::onContextReady() {
                // The three context getters are populated now. Load any previously
                // persisted run count so bumpRunCount() continues across restarts.
                const std::string path = runCountPath(instancePersistencePath());
                if (path.empty()) return;
                std::ifstream in(path);
                if (in) in >> m_runCount;
            }

            // ── Context getters — thin pass-throughs to the SDK base class ──────

            std::string CalcAggregatorImpl::moduleDir() const {
                return modulePath();
            }

            std::string CalcAggregatorImpl::instanceID() const {
                return instanceId();
            }

            bool CalcAggregatorImpl::hasInstanceID() const {
                return !instanceId().empty();
            }

            std::string CalcAggregatorImpl::persistenceDir() const {
                return instancePersistencePath();
            }

            int64_t CalcAggregatorImpl::bumpRunCount() {
                ++m_runCount;
                const std::string path = runCountPath(instancePersistencePath());
                if (!path.empty()) {
                    std::ofstream out(path, std::ios::trunc);
                    out << m_runCount;
                }
                return m_runCount;
            }

            // ── Sync composition: five calls into one map ───────────────────────

            LogosMap CalcAggregatorImpl::computeReport(int64_t a, int64_t b, int64_t n) {
                // modules().calc_module is the generated, std-typed wrapper for the
                // `calc_module` dependency — no raw LogosAPI, no QVariant. Five
                // synchronous calls, composed into one map the caller gets back.
                auto& calc = modules().calc_module;
                LogosMap report;
                report["sum"]        = calc.add(a, b);
                report["product"]    = calc.multiply(a, b);
                report["factorial"]  = calc.factorial(n);
                report["fibonacci"]  = calc.fibonacci(n);
                report["libVersion"] = calc.libVersion();
                return report;
            }

            // ── Async composition: fire now, read the reply later ───────────────

            std::string CalcAggregatorImpl::startAsyncFibonacci(int64_t n) {
                // The generated async overload is `<method>Async(args...,
                // callback, timeout = Timeout())`. It returns immediately; the
                // reply is delivered to the callback on this module's event loop.
                modules().calc_module.fibonacciAsync(n, [this](int64_t value) {
                    m_asyncResult = value;
                });
                return "queued";
            }

            int64_t CalcAggregatorImpl::asyncResult() const {
                return m_asyncResult;
            }

            // ── Event subscription on a dependency ──────────────────────────────

            std::string CalcAggregatorImpl::subscribeVersion() {
                if (m_subscribed) return "ok";
                // Typed subscriber generated from calc_module's `logos_events:`
                // versionReady(const std::string&). The accessor is `on` + the
                // capitalized event name; the callback's arg types match the event.
                m_subscribed = modules().calc_module.onVersionReady(
                    [this](const std::string& version) {
                        m_lastVersionEvent = version;
                    });
                return m_subscribed ? "ok" : "failed";
            }

            std::string CalcAggregatorImpl::lastVersionEvent() const {
                return m_lastVersionEvent;
            }
        post_text: |
          That's the entire module. The three capabilities the SDK base class enables are all here:

          1. **Context properties** — `moduleDir()`, `instanceID()`, `persistenceDir()` just return the base getters; `bumpRunCount()` + `onContextReady()` show the persistence dir used for real, durable state.
          2. **Typed dependency calls** — `computeReport()` uses the **sync** wrappers (`calc.add(...)`, …); `startAsyncFibonacci()` uses the **async** wrapper (`fibonacciAsync(..., callback)`).
          3. **Typed event subscription** — `subscribeVersion()` registers a callback on `calc_module`'s `versionReady` event via the generated `onVersionReady(...)` accessor.

  # ── Step 4: Build ───────────────────────────────────────────────────────────
  - title: "Build the Module"
    step: true
    steps:
      - title: "Add a `.gitignore` and init the repo"
        text: |
          Nix flakes require a git repository. Exclude build artifacts first:
        file:
          path: .gitignore
          language: text
          content: |
            # Nix build output
            result
            result-*

            # CMake build directory
            build/
      - text: "Initialise the repo and stage the files:"
        run: "git init && git add -A"

      - title: "Make sure `calc_module` is built"
        text: |
          The dependency must be built with its shared library present in `lib/` (from [Part 1](tutorial-wrapping-c-library.md#15-build-the-shared-library)). Verify it:
        run: "ls ../logos-calc-module/lib/libcalc.{ext}"
        code_block: |
          ls ../logos-calc-module/lib/libcalc.so    # Linux
          ls ../logos-calc-module/lib/libcalc.dylib  # macOS
        post_text: "If it is missing, build it (as in Part 1, Step 1.5):"
        extra_run:
          run: "test -f ../logos-calc-module/lib/libcalc.{ext} || (cd ../logos-calc-module/lib && gcc {shared_flags} -o libcalc.{ext} libcalc.c && cd -)"
          code_block: |
            cd ../logos-calc-module/lib
            gcc -shared -fPIC -o libcalc.so libcalc.c     # Linux
            # gcc -shared -fPIC -o libcalc.dylib libcalc.c  # macOS
            cd -

      - title: "Lock the dependency and build"
        text: |
          Lock `calc_module` to your local Part 1 checkout. `--override-input` resolves `../logos-calc-module` to an absolute path and records it in `flake.lock`, replacing the placeholder in `flake.nix`:
        run: "nix flake update --override-input calc_module path:../logos-calc-module"
        code_block: |
          nix flake update --override-input calc_module path:../logos-calc-module
      - run: "git add flake.lock"
        post_text: |
          Now build the full package. For a universal module with a dependency, this is where `logos-cpp-generator` runs over both `src/calc_aggregator_impl.h` and `calc_module`'s published LIDL contract, emitting the plugin glue **and** the typed `modules().calc_module` wrapper under `generated_code/` — note `calc_module`'s own plugin is not built here, only its LIDL is read:
      - run: "nix build"

      - title: "Check the output"
        run: "ls -la result/lib/"
        post_text: |
          You should see your plugin (extension depends on platform):

          ```
          calc_aggregator_plugin.so     # Linux
          calc_aggregator_plugin.dylib  # macOS
          ```
      - check_file: "result/lib/calc_aggregator_plugin.{ext}"

  # ── Step 5: Inspect ─────────────────────────────────────────────────────────
  - title: "Inspect the Module"
    step: true
    text: |
      Use `lm` to confirm the dependency and the public API made it into the binary.
    steps:
      - title: "Build `lm`"
        run: "nix build 'github:logos-co/logos-module{release}#lm' --out-link ./lm"

      - title: "View metadata — note the dependency"
        run: "./lm/bin/lm metadata result/lib/calc_aggregator_plugin.{ext}"
        code_block: |
          ./lm/bin/lm metadata result/lib/calc_aggregator_plugin.so    # Linux
          ./lm/bin/lm metadata result/lib/calc_aggregator_plugin.dylib  # macOS
        expect_contains:
          - "Name:         calc_aggregator"
          - "calc_module"
        post_text: |
          ```
          Plugin Metadata:
          ================
          Name:         calc_aggregator
          Version:      1.0.0
          Description:  Composes calc_module and showcases LogosModuleContext
          Author:
          Type:         core
          Dependencies: calc_module
          ```

          `Dependencies: calc_module` confirms the link the builder used to generate the typed wrapper.

      - title: "List methods"
        run: "./lm/bin/lm methods result/lib/calc_aggregator_plugin.{ext}"
        code_block: |
          ./lm/bin/lm methods result/lib/calc_aggregator_plugin.so    # Linux
          ./lm/bin/lm methods result/lib/calc_aggregator_plugin.dylib  # macOS
        expect_contains:
          - "computeReport"
          - "startAsyncFibonacci"
          - "subscribeVersion"
          - "bumpRunCount"
          - "persistenceDir"
        post_text: |
          Every `public` method on the impl is here, published in the **LIDL contract** vocabulary rather than in C++ or Qt names: `int64_t` shows up as `int`, `std::string` as `tstr`, and `LogosMap` (from `computeReport`) as `{tstr: any}`. `lm` is reporting what the module says about itself, and what a module publishes is its contract — the same words the generated `.lidl` uses, and the same words a Rust or Nim module implementing this contract would answer with.

  # ── Step 6: Run it with logoscore ───────────────────────────────────────────
  - title: "Run it with `logoscore`"
    step: true
    text: |
      Now the payoff: run `calc_aggregator` **and** its `calc_module` dependency under `logoscore` and exercise every capability. We use the `logoscore` **daemon** (`-D`) — it keeps each module's process alive between `call` commands, so an event subscription registered by one call is still active when a later call triggers it, and an async reply lands before the call that reads it. (This is the same daemon flow as [Part 1](tutorial-wrapping-c-library.md#step-6-test-with-logoscore).)
    steps:
      - title: "Build the runtime and package both modules"
        text: |
          Build `logoscore` and the package manager, then install **both** modules into a `modules/` directory `logoscore` can scan. The aggregator comes from this project; `calc_module` from your Part 1 checkout:
        run: "nix build 'github:logos-co/logos-logoscore-cli{release}' --out-link ./logos"
      - run: "nix build 'github:logos-co/logos-package-manager{release}#cli' --out-link ./pm"
      - run: "mkdir -p modules"
      - title: "Install calc_aggregator"
        run: "nix build '.#lgx' --out-link result-aggregator-lgx && ./pm/bin/lgpm --modules-dir ./modules install --file result-aggregator-lgx/*.lgx"
        code_block: |
          nix build '.#lgx' --out-link result-aggregator-lgx
          ./pm/bin/lgpm --modules-dir ./modules install --file result-aggregator-lgx/*.lgx
      - title: "Install calc_module (the dependency)"
        run: "nix build 'path:../logos-calc-module#lgx' --out-link result-calc-lgx && ./pm/bin/lgpm --modules-dir ./modules install --file result-calc-lgx/*.lgx"
        code_block: |
          nix build 'path:../logos-calc-module#lgx' --out-link result-calc-lgx
          ./pm/bin/lgpm --modules-dir ./modules install --file result-calc-lgx/*.lgx
        post_text: |
          `modules/` now holds `calc_aggregator/` and `calc_module/`, each with its plugin, libraries, and `manifest.json`.

      - title: "Create a persistence directory and start the daemon"
        text: |
          The host only provisions a per-instance persistence path when you pass `--persistence-path`. Create a directory for it — we reuse the **same** directory across restarts so the instance ID (and therefore the persisted state) is stable:
        run: "mkdir -p calc-data"
        post_text: "Start `logoscore` as a background daemon, pointed at the modules directory and the persistence directory:"
      - run: "./logos/bin/logoscore -D -m ./modules --persistence-path ./calc-data &"
      - run: "sleep 4"
        post_text: "Load both modules. The daemon keeps each module's process alive between `call` commands, which is what lets an event subscription (or an async reply) survive from one call to the next:"
      - run: "./logos/bin/logoscore load-module calc_module"
      - run: "./logos/bin/logoscore load-module calc_aggregator"

      - title: "Read the context properties"
        text: |
          `moduleDir()` / `hasInstanceID()` / `persistenceDir()` return the values the host stamped onto the module. We can't predict the absolute path, but `moduleDir()` must contain the module name:
        run: "./logos/bin/logoscore call calc_aggregator moduleDir"
        expect_contains:
          - "calc_aggregator"
        post_text: "`hasInstanceID()` returns a bool, so a non-empty instance ID shows as `\"result\":true` — an unambiguous signal the host populated `instanceId()` (a plain string getter would read as empty either way):"
      - run: "./logos/bin/logoscore call calc_aggregator hasInstanceID"
        expect_contains:
          - '"result":true'
      - run: "./logos/bin/logoscore call calc_aggregator persistenceDir"
        expect_contains:
          - "calc-data"
          - "calc_aggregator"
        post_text: |
          - `moduleDir()` → the directory the plugin loaded from (contains `calc_aggregator`)
          - `hasInstanceID()` → `"result":true` — the host populated `instanceId()`
          - `persistenceDir()` → a path under your `calc-data/` directory, namespaced by module name and instance ID

      - title: "Compose calc_module synchronously"
        text: |
          `computeReport(a, b, n)` fans out to five typed `calc_module` calls and returns them as one map. With `a=3, b=5, n=10`:
        run: "./logos/bin/logoscore call calc_aggregator computeReport 3 5 10"
        expect_contains:
          - '"sum":8'
          - '"product":15'
          - '"factorial":3628800'
          - '"fibonacci":55'
          - '"libVersion":"1.0.0"'
        post_text: |
          One call, five composed results:

          ```json
          {"method":"computeReport","module":"calc_aggregator","result":{"factorial":3628800,"fibonacci":55,"libVersion":"1.0.0","product":15,"sum":8},"status":"ok"}
          ```

          `sum = 3+5`, `product = 3*5`, `factorial = 10!`, `fibonacci = fib(10)`, and `libVersion` read straight from `calc_module` — all through the generated `modules().calc_module` sync wrappers.

      - title: "Compose calc_module asynchronously"
        text: |
          `startAsyncFibonacci(n)` fires `calc_module.fibonacciAsync(n)` and returns `"queued"` immediately. The reply arrives on the daemon's event loop; the next call, `asyncResult()`, reads what the callback stashed. With `n=20`, `fib(20) = 6765`:
        run: "./logos/bin/logoscore call calc_aggregator startAsyncFibonacci 20"
        expect_contains:
          - '"result":"queued"'
      - run: "sleep 1"
      - run: "./logos/bin/logoscore call calc_aggregator asyncResult"
        expect_contains:
          - '"result":6765'
        post_text: |
          `startAsyncFibonacci` returned before the answer existed; by the time `asyncResult()` runs, the async callback has fired and stored `6765`. That's the typed **async** caller — same wrapper, `<method>Async(..., callback)`.

      - title: "Subscribe to a calc_module event"
        text: |
          The typed event subscription. `subscribeVersion()` registers the callback, `calc_module.libVersionNotify()` makes `calc_module` emit its `versionReady` event, and `lastVersionEvent()` reads what the subscription captured. Because the daemon keeps both modules loaded, the event fires between the calls:
        run: "./logos/bin/logoscore call calc_aggregator subscribeVersion"
        expect_contains:
          - '"result":"ok"'
      - run: "./logos/bin/logoscore call calc_module libVersionNotify"
      - run: "sleep 1"
      - run: "./logos/bin/logoscore call calc_aggregator lastVersionEvent"
        expect_contains:
          - '"result":"1.0.0"'
        post_text: |
          `subscribeVersion()` returned `ok`; the event fired in between; `lastVersionEvent()` returned `1.0.0` — the payload `calc_module` emitted, delivered to the typed callback you registered with `modules().calc_module.onVersionReady(...)`.

      - title: "Persist state across a restart"
        text: |
          `bumpRunCount()` increments a counter saved in the persistence directory. Call it twice — `1`, then `2`:
        run: "./logos/bin/logoscore call calc_aggregator bumpRunCount"
        expect_contains:
          - '"result":1'
      - run: "./logos/bin/logoscore call calc_aggregator bumpRunCount"
        expect_contains:
          - '"result":2'
        post_text: "Now stop the daemon and start a **brand-new** one against the same persistence directory. `onContextReady()` loads the persisted `2` from disk, so the next bump is `3`:"
      - run: "./logos/bin/logoscore stop"
      - run: "sleep 2"
      - run: "./logos/bin/logoscore -D -m ./modules --persistence-path ./calc-data &"
      - run: "sleep 4"
      - run: "./logos/bin/logoscore load-module calc_aggregator"
      - run: "./logos/bin/logoscore call calc_aggregator bumpRunCount"
        expect_contains:
          - '"result":3'
        post_text: |
          The count survived a full process restart — proof the persistence directory is host-owned and durable, and that `onContextReady()` is the right place to rehydrate per-instance state.
      - run: "./logos/bin/logoscore stop"
        post_text: |
          That completes the tour: context properties, durable persistence, sync **and** async typed dependency calls, and a typed event subscription — every capability of `LogosModuleContext`, driven entirely from `logoscore`.

  # ── Recap (prose only) ──────────────────────────────────────────────────────
  - title: "Recap"
    text: |
      | Capability                       | In the code                                              | Seen via `logoscore`                                |
      | -------------------------------- | -------------------------------------------------------- | --------------------------------------------------- |
      | `modulePath()`                   | `moduleDir()`                                            | path contains `calc_aggregator`                     |
      | `instanceId()`                   | `instanceID()` / `hasInstanceID()`                       | `"result":true`                                     |
      | `instancePersistencePath()`      | `persistenceDir()` + `bumpRunCount()` + `onContextReady` | counter climbs `1 → 2 → 3` across a restart         |
      | Typed **sync** dependency call   | `computeReport()` → `calc.add(...)`, …                  | one map of five composed results                    |
      | Typed **async** dependency call  | `startAsyncFibonacci()` → `fibonacciAsync(..., cb)`     | `queued`, then `6765`                               |
      | Typed **event** subscription     | `subscribeVersion()` → `onVersionReady(cb)`             | captured payload `1.0.0` after the event fires      |

      Everything flowed through `modules().calc_module`, the wrapper the builder generated from the `calc_module` dependency — no raw `LogosAPI`, no `QVariant`, no Qt in your code.

      **Next:** give this module a UI by following [Part 2 (QML-only)](tutorial-qml-ui-app.md) or [Part 3 (C++ backend)](tutorial-cpp-ui-app.md), or package it for distribution with `nix build '.#lgx-portable'` (see [Part 1 — Package for Distribution](tutorial-wrapping-c-library.md#package-for-distribution-optional)).