feat: implement match anonymization for non-subscribed orgs

- Add anonymized parameter to match_card component
- Replace avatar with gray circle for anonymized matches
- Replace name/handle with 'Anonymous user' + blur effect
- Hide provider meta information when anonymized
- Preserve country flag display for anonymized matches
- Control anonymization based on hiring_subscription status

Author: zcesur

job_matches_enhancement_prd.md

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+# Job Matches Enhancement PRD
+
+## Overview
+
+Enhance the job matching system in `lib/algora_web/live/org/job_live.ex` to provide better candidate privacy, accurate match counting, improved matching criteria, and visual enhancement with GitHub contribution heatmaps.
+
+## Background
+
+Currently, the job matching system in `lib/algora_web/live/org/job_live.ex` has several limitations:
+1. Matches show full user information (avatar, name, handle) which may not be appropriate for privacy
+2. Match counts are artificially limited (15-50 matches) rather than showing actual match numbers
+3. Matching criteria doesn't properly validate user email availability
+4. Missing visual contribution heatmaps that provide valuable candidate assessment data
+
+## Goals
+
+1. **Anonymize Matches**: Protect candidate privacy by anonymizing user information in match cards
+2. **Accurate Match Counting**: Display real match counts instead of arbitrary limits
+3. **Enhanced Matching Criteria**: Improve matching logic to include email validation
+4. **Visual Enhancement**: Add GitHub contribution heatmaps for better candidate evaluation
+
+## Requirements
+
+### 1. Anonymized Match Display
+
+**Current State:**
+- Matches display full user avatar, name, and GitHub handle
+- All user information is visible in match cards
+
+**Required Changes:**
+- Replace user avatar with a gray circle (`bg-muted` background)
+- Replace user name and handle with "Anonymous user" text
+- Apply `blur-sm` CSS class to anonymized text for visual indication
+- Maintain country flag display if available
+- Keep contribution data and tech stack information visible
+
+**Technical Implementation:**
+```heex
+<!-- Current -->
+<.avatar class="h-12 w-12 rounded-full">
+  <.avatar_image src={@user.avatar_url} alt={@user.name} />
+</.avatar>
+<span class="font-semibold">{@user.name}</span>
+
+<!-- Anonymized -->
+<div class="h-12 w-12 rounded-full bg-muted"></div>
+<span class="font-semibold blur-sm">Anonymous user</span>
+```
+
+### 2. Accurate Match Counting
+
+**Current State:**
+- `Algora.Cloud.truncate_matches/2` limits matches to 15 for non-subscribed orgs
+- `Algora.Cloud.count_matches/1` returns fixed limits (50-100)
+- Display shows truncated count, not actual available matches
+
+**Required Changes:**
+- Modify `get_job_matches/1` in `Algora.Settings` to count all available matches
+- Update match counting logic to return actual numbers instead of arbitrary limits
+- Display format: "X matches found" where X is the real count
+- Maintain existing subscription-based access controls for viewing matches
+
+**Technical Implementation:**
+```elixir
+# In Algora.Settings.get_job_matches/1
+def get_job_matches(job) do
+  total_matches = count_all_matches(job)  # New function
+  available_matches = get_subscription_limited_matches(job)  # Existing logic
+  
+  %{
+    total_count: total_matches,
+    matches: available_matches
+  }
+end
+
+# New helper function
+defp count_all_matches(job) do
+  [
+    tech_stack: job.tech_stack,
+    email_required: true,  # New criteria
+    count_only: true
+  ]
+  |> Algora.Cloud.list_top_matches()
+  |> length()
+end
+```
+
+### 3. Enhanced Matching Criteria
+
+**Current State:**
+- Matching logic in `Algora.Cloud.list_top_matches/1` doesn't validate email availability
+- Users without email addresses may be included in matches
+
+**Required Changes:**
+- Add email validation to matching criteria
+- A user should be considered a match if they have either:
+  - `user.email` field populated, OR
+  - `user.provider_meta["email"]` field populated
+- Update matching query to include this email check
+- Maintain existing tech stack matching logic
+
+**Technical Implementation:**
+```elixir
+# In Algora.Cloud.list_top_matches/1
+def list_top_matches(opts) do
+  # ... existing query setup ...
+  
+  query =
+    query
+    |> where([u], not is_nil(u.email) or fragment("? IS NOT NULL", u.provider_meta["email"]))
+    # ... rest of existing filters ...
+end
+```
+
+### 4. GitHub Contribution Heatmaps
+
+**Current State:**
+- `lib/algora_cloud/live/candidates_live.ex` has heatmap implementation
+- Heatmaps are stored in `user_heatmaps` table
+- Async sync functionality exists via `AlgoraCloud.Profiles.sync_heatmap_by/1`
+
+**Required Changes:**
+- Add heatmap display to match cards in `job_live.ex`
+- Implement similar heatmap component as in `candidates_live.ex`
+- Add async heatmap syncing when socket connects for users without heatmap data
+- Display 17-week contribution grid with color-coded activity levels
+
+**Technical Implementation:**
+
+1. **Update socket assigns in `assign_applicants/1`:**
+```elixir
+defp assign_applicants(socket) do
+  # ... existing code ...
+  
+  # Fetch heatmaps for all developers
+  heatmaps_map =
+    developers
+    |> Enum.map(& &1.id)
+    |> AlgoraCloud.Profiles.list_heatmaps()
+    |> Map.new(fn heatmap -> {heatmap.user_id, heatmap.data} end)
+  
+  # Trigger async sync for missing heatmaps
+  missing_heatmap_users = 
+    developers
+    |> Enum.reject(&Map.has_key?(heatmaps_map, &1.id))
+  
+  if connected?(socket) and length(missing_heatmap_users) > 0 do
+    enqueue_heatmap_sync(missing_heatmap_users)
+  end
+  
+  socket
+  |> assign(:heatmaps_map, heatmaps_map)
+  # ... rest of existing assigns ...
+end
+
+defp enqueue_heatmap_sync(users) do
+  Task.start(fn ->
+    for user <- users do
+      AlgoraCloud.Profiles.sync_heatmap_by(id: user.id)
+    end
+  end)
+end
+```
+
+2. **Add heatmap component to match cards:**
+```heex
+<!-- In match_card function -->
+<div :if={@heatmaps_map[@user.id]} class="mt-4">
+  <.heatmap_display user_id={@user.id} heatmap_data={@heatmaps_map[@user.id]} />
+</div>
+```
+
+3. **Implement heatmap component (based on candidates_live.ex):**
+```heex
+defp heatmap_display(assigns) do
+  ~H"""
+  <div class="mt-4">
+    <div class="flex items-center justify-between mb-2">
+      <div class="text-xs text-muted-foreground uppercase font-semibold">
+        {get_in(@heatmap_data, ["totalContributions"])} contributions in the last year
+      </div>
+    </div>
+    <div class="grid grid-cols-[repeat(17,1fr)] gap-1">
+      <%= for week <- get_in(@heatmap_data, ["weeks"]) |> Enum.take(-17) do %>
+        <div class="grid grid-rows-7 gap-1">
+          <%= for day <- week["contributionDays"] do %>
+            <div
+              class={"h-3 w-3 rounded-sm #{get_contribution_color(day["contributionCount"])}"}
+              title={"#{day["contributionCount"]} contributions on #{format_date(day["date"])}"}
+            >
+            </div>
+          <% end %>
+        </div>
+      <% end %>
+    </div>
+  </div>
+  """
+end
+
+defp get_contribution_color(count) do
+  cond do
+    count == 0 -> "bg-muted/50"
+    count in 1..5 -> "bg-success-400/40"
+    count in 6..10 -> "bg-success-400/50"
+    count in 11..15 -> "bg-success-400/70"
+    count in 16..20 -> "bg-success-400/90"
+    true -> "bg-success-400"
+  end
+end
+```
+
+## Implementation Plan
+
+### Phase 1: Anonymization and Match Counting
+1. Update `match_card/1` function to display anonymized user information
+2. Modify `Algora.Settings.get_job_matches/1` to return actual match counts
+3. Update UI to display real match numbers
+4. Test anonymization with different user types and subscription levels
+
+### Phase 2: Enhanced Matching Criteria
+1. Update `Algora.Cloud.list_top_matches/1` to include email validation
+2. Add database query filters for email requirements
+3. Update matching logic to check both `user.email` and `user.provider_meta["email"]`
+4. Test matching accuracy with email filtering
+
+### Phase 3: Heatmap Integration
+1. Add heatmap data fetching to `assign_applicants/1`
+2. Implement async heatmap syncing for missing data
+3. Add heatmap component to match cards
+4. Test heatmap display and async syncing functionality
+
+### Phase 4: Testing and Optimization
+1. Performance testing with large match sets
+2. UI/UX testing for anonymized cards
+3. Async operation monitoring for heatmap syncing
+4. Cross-browser compatibility testing
+
+## Success Metrics
+
+1. **Privacy Protection**: All match cards show anonymized information for non-subscribed viewers
+2. **Accurate Counts**: Match counts reflect actual available candidates, not artificial limits
+3. **Better Matching**: Only users with email addresses are included in matches
+4. **Enhanced UX**: Heatmaps provide visual contribution data for better candidate assessment
+5. **Performance**: Async heatmap syncing doesn't impact page load times
+
+## Technical Considerations
+
+### Database Impact
+- Heatmap syncing may increase database load
+- Consider implementing rate limiting for async sync operations
+- Monitor performance of email filtering queries
+
+### Caching Strategy
+- Cache heatmap data to reduce GitHub API calls
+- Implement TTL for heatmap data (suggested: 24 hours)
+- Cache match counts to improve performance
+
+### Error Handling
+- Handle GitHub API rate limits gracefully
+- Fallback display when heatmap data is unavailable
+- Graceful degradation if anonymization fails
+
+### Security Considerations
+- Ensure anonymization cannot be bypassed client-side
+- Validate subscription status server-side for match access
+- Protect GitHub API tokens used for heatmap syncing
+
+## Files to Modify
+
+1. **`lib/algora_web/live/org/job_live.ex`** - Main implementation file
+2. **`lib/algora/settings/settings.ex`** - Match counting logic
+3. **`lib/algora_cloud/algora_cloud.ex`** - Matching criteria enhancement
+4. **`lib/algora_cloud/profiles.ex`** - Heatmap syncing (if needed)
+
+## Dependencies
+
+- Existing `AlgoraCloud.Profiles` module for heatmap functionality
+- `user_heatmaps` database table
+- GitHub GraphQL API access for contribution data
+- Existing subscription and authentication systems
+
+## Rollout Strategy
+
+1. **Development**: Implement features in feature branch
+2. **Staging**: Test with sample job postings and user data
+3. **Gradual Rollout**: Deploy to subset of organizations initially
+4. **Full Deployment**: Roll out to all organizations after validation
+5. **Monitoring**: Track performance metrics and user feedback
+
+## Future Enhancements
+
+1. **Advanced Anonymization**: Different levels of anonymization based on subscription tiers
+2. **Enhanced Heatmaps**: Additional metrics like PR review activity, issue contributions
+3. **Real-time Updates**: Live updating of match counts and heatmap data
+4. **Export Functionality**: Allow exporting of match data for subscribed organizations