feat(agents): auto-inject relevant global learnings into planner context (#1830)

* feat(agents): auto-inject relevant global learnings into planner context

* fix(agents): address review feedback for learnings planner injection

- Add features.global_learnings to VALID_CONFIG_KEYS for explicit validation
- Fix error message in cmdConfigSet to mention features.<feature_name> pattern
- Clarify tag syntax in planner injection step (frontmatter tags or objective keywords)

agents/gsd-planner.md

@@ -1007,6 +1007,10 @@ Read the most recent milestone retrospective and cross-milestone trends. Extract
 - **Cost patterns** to inform model selection and agent strategy
 </step>
 
+<step name="inject_global_learnings">
+If `features.global_learnings` is `true`: run `gsd-tools learnings query --tag <phase_tags> --limit 5`, prefix matches with `[Prior learning from <project>]` as weak priors. Project-local decisions take precedence. Skip silently if disabled or no matches. For tags, use PLAN.md frontmatter `tags` field or keywords from the phase objective, comma-separated (e.g. `--tag auth,database,api`).
+</step>
+
 <step name="gather_phase_context">
 Use `phase_dir` from init context (already loaded in load_project_state).
 

get-shit-done/bin/lib/config.cjs

@@ -31,6 +31,8 @@ const VALID_CONFIG_KEYS = new Set([
   'hooks.context_warnings',
   'features.thinking_partner',
   'context',
+  'features.global_learnings',
+  'learnings.max_inject',
   'project_code', 'phase_naming',
   'manager.flags.discuss', 'manager.flags.plan', 'manager.flags.execute',
   'response_language',
@@ -338,7 +340,7 @@ function cmdConfigSet(cwd, keyPath, value, raw) {
   validateKnownConfigKeyPath(keyPath);
 
   if (!isValidConfigKey(keyPath)) {
-    error(`Unknown config key: "${keyPath}". Valid keys: ${[...VALID_CONFIG_KEYS].sort().join(', ')}, agent_skills.<agent-type>`);
+    error(`Unknown config key: "${keyPath}". Valid keys: ${[...VALID_CONFIG_KEYS].sort().join(', ')}, agent_skills.<agent-type>, features.<feature_name>`);
   }
 
   // Parse value (handle booleans, numbers, and JSON arrays/objects)