chore(triage): add build-lookup and r8-mapping skills, wire into triage

.claude/skills/build-lookup/SKILL.md

@@ -0,0 +1,64 @@
+---
+name: build-lookup
+description: >
+  Look up the git commit and GitHub Actions run for a Flipcash versionCode.
+  Usage: /build-lookup <versionCode>
+user-invocable: true
+argument-hint: "<versionCode>"
+allowed-tools:
+  - Bash
+---
+
+# Build Lookup: versionCode to commit + CI run
+
+Resolve a Flipcash versionCode to its git commit and the associated GitHub
+Actions build run.
+
+## Background
+
+The Flipcash versionCode is the output of `git rev-list --count HEAD` at build
+time (see `apps/flipcash/app/build.gradle.kts:20-25`). This means
+**versionCode N = the Nth commit from the root of the repository**.
+
+When someone says "commit 3797" or "build 3797" they mean versionCode 3797.
+
+## Usage
+
+Parse `$ARGUMENTS` for a versionCode (integer). If not provided, ask the user.
+
+Run the helper script:
+
+```bash
+bash .claude/skills/build-lookup/scripts/build-lookup.sh <versionCode>
+```
+
+The script emits JSON:
+
+```json
+{
+  "version_code": 3797,
+  "commit": {
+    "sha": "637722b9c...",
+    "short": "637722b9c",
+    "message": "the commit message",
+    "date": "2026-06-03T..."
+  },
+  "total_commits": 3810,
+  "github_actions": {
+    "run_id": 26846060877,
+    "url": "https://github.com/code-payments/code-android-app/actions/runs/26846060877",
+    "status": "completed",
+    "conclusion": "success"
+  }
+}
+```
+
+`github_actions` is `null` if no matching workflow run was found.
+
+## Output
+
+Present the results clearly:
+
+- **versionCode**: N
+- **Commit**: `<short_sha>` — `<message>` (date)
+- **GitHub Actions**: [Run #ID](url) — status/conclusion

.claude/skills/build-lookup/scripts/build-lookup.sh

@@ -0,0 +1,104 @@
+#!/usr/bin/env bash
+# build-lookup.sh — Resolve a versionCode to its git commit and GitHub Action run.
+#
+# The Flipcash versionCode is derived from `git rev-list --count HEAD` (see
+# apps/flipcash/app/build.gradle.kts:20-25). versionCode N = the Nth commit
+# from the root of the repo.
+#
+# Usage:
+#   ./build-lookup.sh <versionCode>
+#   ./build-lookup.sh 3797
+#
+# Output: JSON with commit_sha, commit_short, commit_message, and (if found)
+#         the GitHub Actions run ID and URL for the Flipcash2 workflow.
+
+set -euo pipefail
+
+if [[ $# -lt 1 ]]; then
+  echo "Usage: build-lookup.sh <versionCode>" >&2
+  exit 1
+fi
+
+VERSION_CODE="$1"
+WORKFLOW_ID="229420296"  # "Flipcash2 Build and Deploy"
+
+# ── Resolve versionCode to commit ───────────────────────────────────
+# versionCode = git rev-list --count HEAD at the time of build.
+# The Nth commit (1-indexed from root) is at position N in `git rev-list --reverse HEAD`.
+# Equivalently: git rev-list HEAD | sed -n '<offset>p' where offset = total - N + 1.
+
+TOTAL=$(git rev-list --count HEAD)
+
+if (( VERSION_CODE > TOTAL )); then
+  echo "ERROR: versionCode $VERSION_CODE exceeds current commit count ($TOTAL)" >&2
+  exit 1
+fi
+
+if (( VERSION_CODE < 1 )); then
+  echo "ERROR: versionCode must be >= 1" >&2
+  exit 1
+fi
+
+OFFSET=$(( TOTAL - VERSION_CODE + 1 ))
+COMMIT_SHA=$(git rev-list HEAD | sed -n "${OFFSET}p")
+COMMIT_SHORT="${COMMIT_SHA:0:9}"
+COMMIT_MESSAGE=$(git log -1 --format='%s' "$COMMIT_SHA")
+COMMIT_DATE=$(git log -1 --format='%aI' "$COMMIT_SHA")
+
+# ── Find GitHub Actions run for this commit ─────────────────────────
+RUN_JSON=""
+RUN_ID=""
+RUN_URL=""
+RUN_STATUS=""
+RUN_CONCLUSION=""
+
+if command -v gh &>/dev/null; then
+  # gh run list --commit requires a full SHA match, so fetch recent runs and
+  # filter by headSha prefix instead. We pull the last 100 runs to cover ~2
+  # weeks of builds.
+  ALL_RUNS=$(gh run list \
+    --workflow="$WORKFLOW_ID" \
+    --json databaseId,url,status,conclusion,headSha \
+    --limit 100 2>/dev/null || true)
+
+  if [[ -n "$ALL_RUNS" ]]; then
+    MATCH=$(echo "$ALL_RUNS" | jq --arg sha "$COMMIT_SHA" '[.[] | select(.headSha == $sha)] | .[0] // empty')
+    if [[ -n "$MATCH" ]]; then
+      RUN_ID=$(echo "$MATCH" | jq -r '.databaseId')
+      RUN_URL=$(echo "$MATCH" | jq -r '.url')
+      RUN_STATUS=$(echo "$MATCH" | jq -r '.status')
+      RUN_CONCLUSION=$(echo "$MATCH" | jq -r '.conclusion')
+    fi
+  fi
+fi
+
+# ── Emit result ─────────────────────────────────────────────────────
+jq -n \
+  --arg version_code    "$VERSION_CODE" \
+  --arg commit_sha      "$COMMIT_SHA" \
+  --arg commit_short    "$COMMIT_SHORT" \
+  --arg commit_message  "$COMMIT_MESSAGE" \
+  --arg commit_date     "$COMMIT_DATE" \
+  --arg total_commits   "$TOTAL" \
+  --arg run_id          "${RUN_ID:-}" \
+  --arg run_url         "${RUN_URL:-}" \
+  --arg run_status      "${RUN_STATUS:-}" \
+  --arg run_conclusion  "${RUN_CONCLUSION:-}" \
+  '{
+    version_code:   ($version_code | tonumber),
+    commit: {
+      sha:     $commit_sha,
+      short:   $commit_short,
+      message: $commit_message,
+      date:    $commit_date
+    },
+    total_commits: ($total_commits | tonumber),
+    github_actions: (
+      if $run_id != "" then {
+        run_id:     ($run_id | tonumber),
+        url:        $run_url,
+        status:     $run_status,
+        conclusion: $run_conclusion
+      } else null end
+    )
+  }'

.claude/skills/r8-mapping/SKILL.md

@@ -0,0 +1,97 @@
+---
+name: r8-mapping
+description: >
+  Download and use the R8 mapping file for a Flipcash release build to
+  deobfuscate stack traces. Usage: /r8-mapping <versionCode>
+user-invocable: true
+argument-hint: "<versionCode>"
+allowed-tools:
+  - Bash
+  - Read
+  - Grep
+---
+
+# R8 Mapping: download and deobfuscate
+
+Download the R8 `mapping.txt` for a Flipcash release build and use it to
+deobfuscate stack traces.
+
+## Background
+
+Release builds are minified/obfuscated by R8. The mapping file is uploaded as
+part of the `release-artifacts` artifact in the "Flipcash2 Build and Deploy"
+GitHub Actions workflow (ID `229420296`). The mapping lives at
+`mapping/release/mapping.txt` inside the artifact.
+
+**R8 class merging**: R8 may merge multiple unrelated classes into one
+obfuscated class. Use line numbers from the stack trace to disambiguate which
+original class a frame belongs to.
+
+## Step 1 — Download the mapping
+
+Parse `$ARGUMENTS` for a versionCode (integer). If not provided, ask the user.
+
+```bash
+bash .claude/skills/r8-mapping/scripts/r8-mapping.sh <versionCode>
+```
+
+The script emits JSON:
+
+```json
+{
+  "mapping_path": "/tmp/r8-mapping-3797/mapping/release/mapping.txt",
+  "run_id": 26846060877,
+  "version_code": 3797,
+  "line_count": 1211075
+}
+```
+
+## Step 2 — Deobfuscate classes
+
+To find what an obfuscated class name maps to:
+
+```bash
+grep " -> <obfuscated_class>:" <mapping_path>
+```
+
+This returns lines like:
+```
+com.original.ClassName -> ag3:
+com.other.MergedClass -> ag3:
+```
+
+Multiple results means R8 merged those classes. Use stack trace line numbers
+to disambiguate — each class section in the mapping contains line-number
+ranges for its methods.
+
+## Step 3 — Deobfuscate methods
+
+After finding the class section, look for method mappings within it:
+
+```bash
+# Find the class section and its method mappings
+grep -A 200 "^com.original.ClassName -> <obfuscated>:" <mapping_path> | head -200
+```
+
+Method lines look like:
+```
+    1:5:void run():123:127 -> run
+    6:10:void otherMethod():45:49 -> a
+```
+
+The format is:
+```
+    <obfuscated_line_start>:<obfuscated_line_end>:<return_type> <original_method>(<params>):<original_line_start>:<original_line_end> -> <obfuscated_method>
+```
+
+Match the line number from the stack trace against `obfuscated_line_start:obfuscated_line_end`
+to find the original method and its original line numbers.
+
+## Output
+
+Present deobfuscated stack frames clearly:
+
+```
+Original: com.original.ClassName.methodName (ClassName.kt:127)
+  Obfuscated: ag3.run (SourceFile:3)
+```

.claude/skills/r8-mapping/scripts/r8-mapping.sh

@@ -0,0 +1,94 @@
+#!/usr/bin/env bash
+# r8-mapping.sh — Download the R8 mapping file for a Flipcash release build.
+#
+# Downloads the `release-artifacts` artifact from the GitHub Actions run
+# associated with a given versionCode, then extracts the R8 mapping.txt.
+#
+# Usage:
+#   ./r8-mapping.sh <versionCode>
+#   ./r8-mapping.sh --run-id <github_actions_run_id>
+#
+# Output: JSON with the path to the downloaded mapping file and metadata.
+# The mapping file is saved to /tmp/r8-mapping-<versionCode>/mapping/release/mapping.txt
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../../../.." && pwd)"
+BUILD_LOOKUP="$REPO_ROOT/.claude/skills/build-lookup/scripts/build-lookup.sh"
+WORKFLOW_ID="229420296"
+
+# ── Argument parsing ────────────────────────────────────────────────
+RUN_ID=""
+VERSION_CODE=""
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --run-id) RUN_ID="$2"; shift 2 ;;
+    *)        VERSION_CODE="$1"; shift ;;
+  esac
+done
+
+# ── Resolve run ID if only versionCode given ────────────────────────
+if [[ -z "$RUN_ID" && -n "$VERSION_CODE" ]]; then
+  LOOKUP_JSON=$(bash "$BUILD_LOOKUP" "$VERSION_CODE")
+
+  RUN_ID=$(echo "$LOOKUP_JSON" | jq -r '.github_actions.run_id // empty')
+  COMMIT_SHA=$(echo "$LOOKUP_JSON" | jq -r '.commit.sha')
+
+  if [[ -z "$RUN_ID" ]]; then
+    echo "ERROR: No GitHub Actions run found for versionCode $VERSION_CODE (commit $COMMIT_SHA)" >&2
+    echo "Try: gh run list --workflow=$WORKFLOW_ID --commit=${COMMIT_SHA:0:9} --limit=10" >&2
+    exit 1
+  fi
+elif [[ -z "$RUN_ID" ]]; then
+  echo "Usage: r8-mapping.sh <versionCode>" >&2
+  echo "       r8-mapping.sh --run-id <run_id>" >&2
+  exit 1
+fi
+
+# ── Download artifact ───────────────────────────────────────────────
+DEST_DIR="/tmp/r8-mapping-${VERSION_CODE:-$RUN_ID}"
+MAPPING_PATH="$DEST_DIR/mapping/release/mapping.txt"
+
+if [[ -f "$MAPPING_PATH" ]]; then
+  # Already downloaded, skip
+  LINE_COUNT=$(wc -l < "$MAPPING_PATH" | tr -d ' ')
+else
+  rm -rf "$DEST_DIR"
+  mkdir -p "$DEST_DIR"
+
+  echo "Downloading release-artifacts from run $RUN_ID..." >&2
+  gh run download "$RUN_ID" \
+    -n release-artifacts \
+    -D "$DEST_DIR" 2>&1 >&2
+
+  if [[ ! -f "$MAPPING_PATH" ]]; then
+    # Try alternate path — artifact may have different structure
+    ALT=$(find "$DEST_DIR" -name "mapping.txt" -type f 2>/dev/null | head -1)
+    if [[ -n "$ALT" ]]; then
+      MAPPING_PATH="$ALT"
+    else
+      echo "ERROR: mapping.txt not found in downloaded artifacts" >&2
+      echo "Contents of $DEST_DIR:" >&2
+      find "$DEST_DIR" -type f >&2
+      exit 1
+    fi
+  fi
+
+  LINE_COUNT=$(wc -l < "$MAPPING_PATH" | tr -d ' ')
+  echo "Downloaded mapping.txt ($LINE_COUNT lines)" >&2
+fi
+
+# ── Emit result ─────────────────────────────────────────────────────
+jq -n \
+  --arg mapping_path  "$MAPPING_PATH" \
+  --arg run_id        "$RUN_ID" \
+  --arg version_code  "${VERSION_CODE:-unknown}" \
+  --arg line_count    "$LINE_COUNT" \
+  '{
+    mapping_path: $mapping_path,
+    run_id:       ($run_id | tonumber),
+    version_code: (if $version_code != "unknown" then ($version_code | tonumber) else null end),
+    line_count:   ($line_count | tonumber)
+  }'