store: Docker Tags Composite Action: Three-Channel Branch-Based Tag Resolution

graph/decisions/docker-tags-composite-action-three-channel-branch-based-tag-f67518.md

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+---
+id: f6751853-4ca9-4c82-a767-3348ad6275a7
+type: decision
+title: "Docker Tags Composite Action: Three-Channel Branch-Based Tag Resolution"
+tags: [gitea-actions, docker, ci-cd, composite-action, docker-tags, calver]
+importance: 0.8
+confidence: 0.8
+created: "2026-03-05T03:31:12.382315+00:00"
+updated: "2026-03-05T03:31:12.382315+00:00"
+---
+
+# Docker Tags Composite Action: Three-Channel Branch-Based Tag Resolution
+
+## Context
+
+Created `docker-tags/action.yml` in the `cal/gitea-actions` shared composite actions repository to standardize Docker image tagging across CI/CD pipelines.
+
+## Problem
+
+Consuming repos were duplicating conditional build logic to handle different Docker tags for different branches, leading to inconsistent tag schemes and maintenance overhead.
+
+## Decision
+
+Centralize Docker tag resolution into a reusable composite action with three defined channels:
+
+| Branch | Channel | Tags Generated |
+|--------|---------|----------------|
+| `main` | `stable` | `latest`, `<calver>`, `<calver>-<sha>` |
+| `next-release` | `rc` | `next-release`, `<calver>-rc`, `<calver>-rc-<sha>` |
+| anything else | `dev` | `dev`, `dev-<sha>` |
+
+## Action Interface
+
+**Inputs:**
+- `image` — Docker image name (e.g. `manticorum67/paper-dynasty-discordapp`)
+- `version` — CalVer string (from calver composite action)
+- `sha_short` — Short git SHA
+
+**Outputs:**
+- `tags` — comma-separated list of full image:tag strings
+- `channel` — one of `stable`, `rc`, `dev`
+- `primary_tag` — `latest`, `next-release`, or `dev`
+
+## Rationale
+
+- Single source of truth for tag conventions across all projects
+- Consuming repos only need to pass image + version + sha
+- Channel output enables downstream conditional logic (e.g., gate release creation on `channel == 'stable'`, skip Discord notify on `channel == 'dev'`)