feat(cel): custom data transformation functions (#14) (#21)

* docs: add spec for data transformation CEL functions (#14)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add implementation plan for data transformation CEL functions (#14)

12-task plan: macro tests, string/type/collection/JSON/time functions,
obj() construction, docs updates, and example workflows.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* test(cel): add coverage for built-in map/filter/exists/all macros

* feat(cel): add toLower, toUpper, trim string functions

Registers custom string member overloads via cel.Lib and wires them
into NewEvaluator through a central customFunctions() registration point.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(cel): add replace and split string functions

* feat(cel): add parseInt, parseFloat, toString type coercion functions

* feat(cel): add obj() map construction function

* feat(cel): add default() null coalescing and flatten() functions

* feat(cel): add jsonEncode and jsonDecode functions

* feat(cel): add timestamp and formatTimestamp date/time functions

* docs: add custom CEL functions and macros to expressions reference (#14)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat: add data transformation and AI enrichment example workflows (#14)

* docs: add data transformation patterns guide (#14)

Covers three patterns — CEL-only structural transforms, AI-powered semantic
transforms, and hybrid workflows that combine both. Includes a decision guide
and a quick-reference table of all available CEL extension functions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: address CodeRabbit review — null handling, date formats, docs, tests (#14)

- default(): fall through to rhs when lhs is null (types.NullValue)
- parseTimestamp(): try RFC3339Nano, bare ISO date, US date, and named-month formats before erroring
- expressions.md: remove undeclared `now` variable from two examples
- data-transformations.md: add missing exists_one row to list-macros table
- data-transform-api-to-db.yaml: simplify to single-user fetch+insert (fixes broken batch param shape)
- functions_test.go: add null/fallback tests for default(), edge-case tests for flatten(), and new format tests for parseTimestamp()

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: address PR #21 review — non-strict default, jsonDecode precision, docs accuracy

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address PR #21 review round 3 — test coverage, trailing JSON, docs accuracy

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address PR #21 review round 4 — EOF trailing check, docs, plan cleanup

- jsonDecode: replace dec.More() with dec.Decode(&trailing) EOF check
  to catch all trailing data (e.g., "{}]", "1}")
- Add trailing_bracket and trailing_brace regression tests
- Update parseTimestamp description in data-transformations.md to list
  all accepted formats
- Plan: rename TestFunc_Timestamp to TestFunc_ParseTimestamp, add
  golangci-lint to final validation checklist

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address PR #21 review round 5 — precision, flatten, plan accuracy

- normalizeJSONNumbers: only use float64 for decimals/exponents, preserve
  overflow integers as strings to avoid silent precision loss
- flatten: initialize result as make([]any, 0) so empty lists return
  non-nil empty slice
- Add large_integer_preserved test for jsonDecode
- Plan: remove dead split() variable, replace variadic obj() with
  fixed-arity overloads, add jsonDecode EOF check, fix timestamp refs
- data-transformations.md: note obj() 5-pair limit

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(plan): correct test selector to TestFunc_ParseTimestamp

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: remove force-added superpowers docs from tracking

These internal process docs (specs, plans) are already in .gitignore
but were force-added during development. Files remain on disk but are
no longer tracked by git.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* 📝 CodeRabbit Chat: Add generated unit tests

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: 3 people

docs/superpowers/plans/2026-03-24-init-connection-recovery.md

@@ -0,0 +1,65 @@
+name: ai-data-enrichment
+description: >
+  Fetches support tickets, uses an AI model to classify priority and
+  extract key entities, then stores the enriched data. Demonstrates
+  using AI for transforms that require interpretation rather than
+  simple structural mapping.
+
+inputs:
+  ticket_api_url:
+    type: string
+    description: URL to fetch support tickets from
+
+steps:
+  - name: fetch-tickets
+    action: http/request
+    timeout: "15s"
+    params:
+      method: GET
+      url: "{{ inputs.ticket_api_url }}"
+      headers:
+        Accept: "application/json"
+
+  - name: classify
+    action: ai/completion
+    credential: openai
+    timeout: "60s"
+    params:
+      model: gpt-4o
+      system_prompt: >
+        You are a support ticket classifier. Given a ticket, determine
+        the priority (critical, high, medium, low), category, and extract
+        any mentioned product names or error codes.
+      prompt: "Classify this ticket: {{ steps['fetch-tickets'].output.body }}"
+      output_schema:
+        type: object
+        properties:
+          priority:
+            type: string
+            enum: [critical, high, medium, low]
+          category:
+            type: string
+          products:
+            type: array
+            items:
+              type: string
+          error_codes:
+            type: array
+            items:
+              type: string
+        required: [priority, category, products, error_codes]
+        additionalProperties: false
+
+  - name: store-enriched
+    action: postgres/query
+    credential: app-db
+    if: "steps.classify.output.json.priority == 'critical' || steps.classify.output.json.priority == 'high'"
+    params:
+      query: >
+        INSERT INTO urgent_tickets (priority, category, products, raw_body)
+        VALUES ($1, $2, $3, $4)
+      args:
+        - "{{ steps.classify.output.json.priority }}"
+        - "{{ steps.classify.output.json.category }}"
+        - "{{ jsonEncode(steps.classify.output.json.products) }}"
+        - "{{ steps['fetch-tickets'].output.body }}"

docs/superpowers/specs/2026-03-24-init-connection-recovery-design.md

@@ -0,0 +1,25 @@
+name: data-transform-api-to-db
+description: >
+  Fetches a user from an API, transforms the record using CEL expressions
+  to match a database schema, and inserts the normalized data into Postgres.
+  Demonstrates toLower() and string functions without requiring an AI model.
+
+steps:
+  - name: fetch-user
+    action: http/request
+    timeout: "15s"
+    params:
+      method: GET
+      url: "https://jsonplaceholder.typicode.com/users/1"
+      headers:
+        Accept: "application/json"
+
+  - name: store-user
+    action: postgres/query
+    credential: app-db
+    params:
+      query: "INSERT INTO users (username, email, city) VALUES ($1, $2, $3)"
+      args:
+        - "{{ steps['fetch-user'].output.json.username.toLower() }}"
+        - "{{ steps['fetch-user'].output.json.email.toLower() }}"
+        - "{{ steps['fetch-user'].output.json.address.city }}"

examples/ai-data-enrichment.yaml

@@ -28,12 +28,15 @@ type Evaluator struct {
 
 // NewEvaluator creates a CEL evaluator with the standard Mantle expression environment.
 func NewEvaluator() (*Evaluator, error) {
-	env, err := cel.NewEnv(
+	opts := []cel.EnvOption{
 		cel.Variable("steps", cel.MapType(cel.StringType, cel.DynType)),
 		cel.Variable("inputs", cel.MapType(cel.StringType, cel.DynType)),
 		cel.Variable("env", cel.MapType(cel.StringType, cel.StringType)),
 		cel.Variable("trigger", cel.MapType(cel.StringType, cel.DynType)),
-	)
+	}
+	opts = append(opts, customFunctions()...)
+
+	env, err := cel.NewEnv(opts...)
 	if err != nil {
 		return nil, fmt.Errorf("creating CEL environment: %w", err)
 	}