diff --git a/.github/ISSUE_TEMPLATE/gp-01.yml b/.github/ISSUE_TEMPLATE/gp-01.yml
new file mode 100644
index 00000000..fceb1fde
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/gp-01.yml
@@ -0,0 +1,113 @@
+name: "GP-01 — GEMS Language evolution impact on GemsPy"
+description: Track updates to the GemsPy interpreter triggered by a new GEMS Language version
+title: "[GP-01] GEMS Language update — GemsPy impact"
+labels: ["GP-01", "gems-language-update"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        **Process GP-01** — Triggered by a new GEMS Language version that requires changes to GemsPy parsing, execution, or behavior.
+
+        > **Deviation from standard workflow — Step 4:** introduce version-gated behavior if needed; GemsPy must support multiple GEMS Language versions simultaneously; update parsing and execution layers accordingly.
+
+  - type: input
+    id: gems_new_version
+    attributes:
+      label: New GEMS Language Version
+      placeholder: "e.g. 1.3.0"
+    validations:
+      required: true
+
+  - type: input
+    id: gems_previous_version
+    attributes:
+      label: Previous Tracked Version
+      placeholder: "e.g. 1.2.0"
+    validations:
+      required: true
+
+  - type: textarea
+    id: trigger
+    attributes:
+      label: Trigger
+      description: What changed in the new GEMS Language version? Link to the GEMS release notes or changelog.
+    validations:
+      required: true
+
+  - type: textarea
+    id: impact
+    attributes:
+      label: Impact Analysis
+      description: |
+        Assess the impact on:
+        - **Grammar** — does `grammar/Expr.g4` need updating?
+        - **Parsing layer** — does the ANTLR-generated parser or expression AST need updating?
+        - **Execution layer** — does model loading, constraint building, or variable resolution need updating?
+        - **Version-gated behavior** — does GemsPy need to support both old and new syntax simultaneously?
+        - **Results** — are solver output values expected to change?
+        - **Compatibility** — breaking vs backward-compatible?
+    validations:
+      required: true
+
+  - type: textarea
+    id: validation_strategy
+    attributes:
+      label: Validation Strategy
+      description: |
+        Describe the regression and E2E validation approach:
+        - Which reference studies cover the new/changed syntax?
+        - Are solver results expected to differ? If yes, why?
+        - How will backward compatibility with old syntax be verified?
+    validations:
+      required: true
+
+  - type: textarea
+    id: checklist
+    attributes:
+      label: Process Checklist
+      value: |
+        ### Step 1 — Issue Creation
+        - [x] Issue created and linked to process GP-01
+
+        ### Step 2 — Triage
+        - [ ] Process confirmed applicable
+        - [ ] Assigned to responsible contributor
+        - [ ] Priority and milestone set (if applicable)
+
+        ### Step 3 — Impact Analysis
+        - [ ] GEMS Language changelog reviewed for GemsPy-relevant changes
+        - [ ] Grammar impact assessed (`grammar/Expr.g4`)
+        - [ ] Parsing layer impact assessed (`expression/`, ANTLR-generated files)
+        - [ ] Execution layer impact assessed (`simulation/`, `study/`)
+        - [ ] Version-gated behavior required? (yes/no — document decision)
+        - [ ] Results impact assessed (solver values expected to change?)
+        - [ ] Breaking vs backward-compatible change identified
+
+        ### Step 4 — Implementation ⚠️ version-gated behavior may be required
+        - [ ] Grammar updated (`grammar/Expr.g4`) if needed — do not edit ANTLR-generated files directly
+        - [ ] ANTLR parser regenerated if grammar changed
+        - [ ] Parsing and execution layers updated (`expression/`, `simulation/`, `study/`)
+        - [ ] Version-gated behavior introduced if GemsPy must support both old and new syntax
+
+        ### Step 5 — Testing & Validation ⚠️ regression suite covering old and new syntax required
+        - [ ] At least one reference E2E study validating new language feature added or updated
+        - [ ] Regression tests covering old syntax still pass
+        - [ ] If results expected to change: before/after comparison documented
+        - [ ] If results must not change: confirmed via tests
+
+        ### Step 6 — CI Validation
+        - [ ] Type checking passes (`mypy`)
+        - [ ] Formatting passes (`black`, `isort`)
+        - [ ] All tests pass in CI (`pytest`)
+
+        ### Step 7 — Review & Merge
+        - [ ] PR reviewed; documentation changes included
+
+        ### Step 8 — Versioning
+        - [ ] `pyproject.toml` version bumped (Major if breaking language change, Minor otherwise)
+
+        ### Step 9 — Supporting Files
+        - [ ] `AGENTS.md` reviewed for impact and updated if needed
+
+        ### Step 10 — Release
+        - [ ] If a release is needed: follow the release process in the Developer Guidelines
diff --git a/.github/ISSUE_TEMPLATE/gp-02.yml b/.github/ISSUE_TEMPLATE/gp-02.yml
new file mode 100644
index 00000000..28a42926
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/gp-02.yml
@@ -0,0 +1,113 @@
+name: "GP-02 — GemsPy internal development"
+description: Track internal bug fixes, new GemsPy features, or code improvements not driven by a GEMS Language release
+title: "[GP-02] "
+labels: ["GP-02"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        **Process GP-02** — Triggered by internal initiative to fix, improve, or extend GemsPy. Not driven by a new GEMS Language version.
+
+        > **Deviation from standard workflow — Step 3:** extended impact analysis on results is required. You must explicitly state whether solver results are expected to change, and if so, document the reasoning.
+
+  - type: dropdown
+    id: component
+    attributes:
+      label: Affected Component
+      options:
+        - Expression parsing / grammar (expression/, grammar/)
+        - Optimization problem construction (simulation/)
+        - Study loading / model resolution (study/)
+        - Decomposition / optim-config (optim_config/)
+        - Library resolution (libs/)
+        - Other (specify in description)
+    validations:
+      required: true
+
+  - type: dropdown
+    id: change_type
+    attributes:
+      label: Type of Change
+      description: Determines the semantic version impact.
+      options:
+        - "Major: backward-incompatible change or major new feature (e.g. rolling horizon)"
+        - "Minor: bug fix or backward-compatible new feature (e.g. new operator)"
+        - "Patch: dependency update, code optimisation, or internal refactor with no syntax impact"
+    validations:
+      required: true
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: What change is being proposed and why?
+    validations:
+      required: true
+
+  - type: textarea
+    id: results_impact
+    attributes:
+      label: Results Impact
+      description: |
+        Are solver output values expected to change?
+        - If yes: describe the before/after difference and why it is intended.
+        - If no: this must be confirmed via tests.
+    validations:
+      required: true
+
+  - type: textarea
+    id: validation_strategy
+    attributes:
+      label: Validation Strategy
+      description: |
+        Describe the validation approach:
+        - Which unit tests cover the changed component?
+        - Which E2E studies confirm solver equivalence (if results must not change)?
+        - If results are expected to change, which reference studies document the new expected behavior?
+    validations:
+      required: true
+
+  - type: textarea
+    id: checklist
+    attributes:
+      label: Process Checklist
+      value: |
+        ### Step 1 — Issue Creation
+        - [x] Issue created and linked to process GP-02
+
+        ### Step 2 — Triage
+        - [ ] Process confirmed applicable
+        - [ ] Assigned to responsible contributor
+        - [ ] Priority and milestone set (if applicable)
+
+        ### Step 3 — Impact Analysis ⚠️ extended results analysis required
+        - [ ] Affected modules identified
+        - [ ] Results impact explicitly stated: change intended / no change intended
+        - [ ] If results expected to change: before/after difference described and justified
+        - [ ] Breaking vs backward-compatible change determined
+
+        ### Step 4 — Implementation
+        - [ ] Code changes implemented
+        - [ ] Backward compatibility maintained unless explicitly intended as breaking
+
+        ### Step 5 — Testing & Validation
+        - [ ] If results expected to change: reference studies updated with new expected values
+        - [ ] If results must not change: solver equivalence confirmed via tests
+        - [ ] Unit tests cover changed components
+
+        ### Step 6 — CI Validation
+        - [ ] Type checking passes (`mypy`)
+        - [ ] Formatting passes (`black`, `isort`)
+        - [ ] All tests pass in CI (`pytest`)
+
+        ### Step 7 — Review & Merge
+        - [ ] PR reviewed; documentation changes included
+
+        ### Step 8 — Versioning
+        - [ ] `pyproject.toml` version bumped
+
+        ### Step 9 — Supporting Files
+        - [ ] `AGENTS.md` reviewed for impact and updated if needed
+
+        ### Step 10 — Release
+        - [ ] If a release is needed: follow the release process in the Developer Guidelines
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 00000000..2bb774b5
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,23 @@
+## Process ID
+
+<!-- Which governance process does this PR fall under? -->
+<!-- GP-01 | GP-02 | N/A -->
+
+**Process:**
+
+## Description
+
+<!-- What does this PR change and why? -->
+
+## Impact Analysis
+
+<!-- Which modules are affected (expression/, simulation/, study/, optim_config/)? -->
+<!-- Are solver output values expected to change? If yes, document why. -->
+
+## Checklist
+
+- [ ] Unit tests pass (`pytest`)
+- [ ] Type checking passes (`mypy`)
+- [ ] Formatting passes (`black`, `isort`)
+- [ ] `pyproject.toml` version bumped if applicable
+- [ ] `AGENTS.md` reviewed for impact and updated if needed
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2778d5a8..09ccaf09 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,10 +11,10 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v6
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.11
 
diff --git a/.github/workflows/notify-gemspy-release.yml b/.github/workflows/notify-gemspy-release.yml
new file mode 100644
index 00000000..6e6056ad
--- /dev/null
+++ b/.github/workflows/notify-gemspy-release.yml
@@ -0,0 +1,165 @@
+name: Notify dependents — GemsPy new release
+
+on:
+  release:
+    types: [published]
+
+permissions:
+  contents: read
+
+jobs:
+  notify:
+    name: Create issue in dependent repositories
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Get release version
+        id: version
+        run: |
+          VERSION="${{ github.event.release.tag_name }}"
+          VERSION="${VERSION#v}"
+          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
+          echo "Released version: $VERSION"
+
+      - name: Notify GEMS repository
+        uses: actions/github-script@v9
+        with:
+          github-token: ${{ secrets.GEMS_REPO_PAT }}
+          script: |
+            const version = '${{ steps.version.outputs.version }}';
+            const title = `[GEMSPY UPDATE] New release: v${version}`;
+            const owner = context.repo.owner;
+
+            const existing = await github.rest.issues.listForRepo({
+              owner: owner,
+              repo: 'GEMS',
+              state: 'open',
+            });
+
+            const duplicate = existing.data.find(i => i.title.includes(`v${version}`));
+            if (duplicate) {
+              console.log(`Issue already exists in GEMS: #${duplicate.number} — skipping.`);
+              return;
+            }
+
+            const body = [
+              '> This issue was automatically created by the `notify-gemspy-release` workflow in GemsPy.',
+              '',
+              '## New Version Detected',
+              '',
+              '| | |',
+              '|---|---|',
+              `| **New version** | \`${version}\` |`,
+              `| **PyPI page** | https://pypi.org/project/gemspy/${version}/ |`,
+              `| **Release notes** | https://github.com/${owner}/GemsPy/releases/tag/v${version} |`,
+              '',
+              '## Triage',
+              '',
+              '- [ ] GemsPy changelog reviewed',
+              '- [ ] No action needed (if release has no impact on GEMS)',
+            ].join('\n');
+
+            const result = await github.rest.issues.create({
+              owner: owner,
+              repo: 'GEMS',
+              title: title,
+              body: body,
+            });
+
+            console.log(`Issue created in GEMS: #${result.data.number} — ${result.data.html_url}`);
+
+      - name: Notify AntaresLegacyModels-to-GEMS-Converter repository
+        uses: actions/github-script@v9
+        with:
+          github-token: ${{ secrets.ANTARES_LEGACY_CONVERTER_PAT }}
+          script: |
+            const version = '${{ steps.version.outputs.version }}';
+            const title = `[GEMSPY UPDATE] New release: v${version}`;
+            const owner = context.repo.owner;
+
+            const existing = await github.rest.issues.listForRepo({
+              owner: owner,
+              repo: 'AntaresLegacyModels-to-GEMS-Converter',
+              state: 'open',
+            });
+
+            const duplicate = existing.data.find(i => i.title.includes(`v${version}`));
+            if (duplicate) {
+              console.log(`Issue already exists in AntaresLegacyModels-to-GEMS-Converter: #${duplicate.number} — skipping.`);
+              return;
+            }
+
+            const body = [
+              '> This issue was automatically created by the `notify-gemspy-release` workflow in GemsPy.',
+              '',
+              '## New Version Detected',
+              '',
+              '| | |',
+              '|---|---|',
+              `| **New version** | \`${version}\` |`,
+              `| **PyPI page** | https://pypi.org/project/gemspy/${version}/ |`,
+              `| **Release notes** | https://github.com/${owner}/GemsPy/releases/tag/v${version} |`,
+              '',
+              '## Triage',
+              '',
+              '- [ ] GemsPy changelog reviewed',
+              '- [ ] A2G-04 issue opened (if API changes affect GEMS study generation, model validation, or simulation output)',
+              '- [ ] No action needed (if release has no impact on the converter)',
+            ].join('\n');
+
+            const result = await github.rest.issues.create({
+              owner: owner,
+              repo: 'AntaresLegacyModels-to-GEMS-Converter',
+              title: title,
+              body: body,
+            });
+
+            console.log(`Issue created in AntaresLegacyModels-to-GEMS-Converter: #${result.data.number} — ${result.data.html_url}`);
+
+      - name: Notify GEMS-ViewsBuilder repository
+        uses: actions/github-script@v9
+        with:
+          github-token: ${{ secrets.GEMS_VIEWS_BUILDER_PAT }}
+          script: |
+            const version = '${{ steps.version.outputs.version }}';
+            const title = `[GEMSPY UPDATE] New release: v${version}`;
+            const owner = context.repo.owner;
+
+            const existing = await github.rest.issues.listForRepo({
+              owner: owner,
+              repo: 'GEMS-ViewsBuilder',
+              state: 'open',
+            });
+
+            const duplicate = existing.data.find(i => i.title.includes(`v${version}`));
+            if (duplicate) {
+              console.log(`Issue already exists in GEMS-ViewsBuilder: #${duplicate.number} — skipping.`);
+              return;
+            }
+
+            const body = [
+              '> This issue was automatically created by the `notify-gemspy-release` workflow in GemsPy.',
+              '',
+              '## New Version Detected',
+              '',
+              '| | |',
+              '|---|---|',
+              `| **New version** | \`${version}\` |`,
+              `| **PyPI page** | https://pypi.org/project/gemspy/${version}/ |`,
+              `| **Release notes** | https://github.com/${owner}/GemsPy/releases/tag/v${version} |`,
+              '',
+              '## Triage',
+              '',
+              '- [ ] GemsPy changelog reviewed',
+              '- [ ] `gemspy` dependency version updated in `pyproject.toml` (if new features or fixes are required)',
+              '- [ ] No action needed (if release has no impact on GEMS-ViewsBuilder)',
+            ].join('\n');
+
+            const result = await github.rest.issues.create({
+              owner: owner,
+              repo: 'GEMS-ViewsBuilder',
+              title: title,
+              body: body,
+            });
+
+            console.log(`Issue created in GEMS-ViewsBuilder: #${result.data.number} — ${result.data.html_url}`);
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 69d6bd6c..6ee6ea13 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -22,9 +22,9 @@ jobs:
     environment: PyPi
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: '3.11'
 
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 00000000..57af52b2
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,5 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+For full project context, architecture, conventions, and critical rules, see [AGENTS.md](AGENTS.md) — read it before making any changes.