change to inline distro support model

.github/workflows/ci.yml

@@ -3,34 +3,14 @@ name: ci
 on:
   pull_request:
   push:
-    branches: [main, humble, jazzy, kilted]
+    branches: [main]
 
 jobs:
-  setup:
-    runs-on: ubuntu-latest
-    outputs:
-      distros: ${{ steps.set-distros.outputs.distros }}
-    steps:
-      - id: set-distros
-        run: |
-          # For PRs, use the target branch; for pushes, use the branch name
-          BRANCH="${{ github.base_ref || github.ref_name }}"
-          if [[ "$BRANCH" == "humble" ]]; then
-            echo 'distros=["humble"]' >> "$GITHUB_OUTPUT"
-          elif [[ "$BRANCH" == "jazzy" ]]; then
-            echo 'distros=["jazzy"]' >> "$GITHUB_OUTPUT"
-          elif [[ "$BRANCH" == "kilted" ]]; then
-            echo 'distros=["kilted"]' >> "$GITHUB_OUTPUT"
-          else
-            echo 'distros=["jazzy","kilted"]' >> "$GITHUB_OUTPUT"
-          fi
-
   build-and-test:
-    needs: setup
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ros_distro: ${{ fromJson(needs.setup.outputs.distros) }}
+        ros_distro: [humble, jazzy, kilted]
       fail-fast: false
     name: build (${{ matrix.ros_distro }})
     steps:

README.md

@@ -1586,27 +1586,17 @@ All pull requests are checked for DCO sign-off via CI. Commits without a `Signed
 
 ### Branching Strategy
 
-Development happens on `main`. Each supported ROS distro has a dedicated branch (e.g., `humble`, `jazzy`) that is **continuously rebased** onto `main`.
+All supported ROS distros build from a single `main` branch. There are no per-distro branches. Distro differences are expressed inline in the code (C++ `#if` on rclcpp version macros, Python `try/except ImportError`, CMake version checks, `package.xml` format-3 `condition` attributes) and distro support is exercised as a CI matrix over `{humble, jazzy, kilted}`.
 
-```
-main:     A --- B --- C --- D
-                              \
-humble:                        D --- H1 --- H2  (distro-specific patches)
-jazzy:                         D --- J1          (distro-specific patches)
-```
-
-**How it works:**
+Releases are ordinary tags on `main` (e.g. `v0.4.0`), consumed by bloom and conda as a matrix over distros from the same tag.
 
-- All new features and bug fixes are developed against `main` via pull requests.
-- Distro branches carry a small number of distro-specific patches (e.g., API compatibility shims, version pins) as commits on top of `main`.
-- After `main` advances, distro branches are rebased onto it, keeping the patches at the tip.
-- Distro branches are **force-pushed** after each rebase.
+For the full rationale, design, and migration notes, see [`docs/branching-and-releases.md`](docs/branching-and-releases.md).
 
 **Guidelines for contributors:**
 
-- For general features and fixes, base your branch on `main` and open your PR against `main`.
-- For distro-specific fixes, base your branch on the target distro branch and open your PR directly against it. Distro PRs are **squash-merged** to keep the patch stack clean for rebasing.
-- Do not merge distro branches into `main` or vice versa — the relationship is always rebase, never merge.
+- Base your branch on `main` and open your PR against `main`.
+- PR CI runs the build+test pipeline per distro. `jazzy` and `kilted` are required checks; `humble` currently runs non-blocking while we work through its remaining failures.
+- If your change needs a distro-specific accommodation, add it inline at the point of difference rather than in a separate branch.
 
 ## License