feat(ultraplan-local): v1.6.0 — /ultraresearch-local deep research command

Add /ultraresearch-local for structured research combining local codebase
analysis with external knowledge via parallel agent swarms. Produces research
briefs with triangulation, confidence ratings, and source quality assessment.

New command: /ultraresearch-local with modes --quick, --local, --external, --fg.
New agents: research-orchestrator (opus), docs-researcher, community-researcher,
security-researcher, contrarian-researcher, gemini-bridge (all sonnet).
New template: research-brief-template.md.

Integration: --research flag in /ultraplan-local accepts pre-built research
briefs (up to 3), enriches the interview and exploration phases. Planning
orchestrator cross-references brief findings during synthesis.

Design principle: Context Engineering — right information to right agent at
right time. Research briefs are structured artifacts in the pipeline:
ultraresearch → brief → ultraplan --research → plan → ultraexecute.

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

plugins/linkedin-thought-leadership/references/linkedin-formats.md

@@ -46,20 +46,21 @@ Choosing the right format isn't just about engagement rates—it's about underst
    - Why it works: Encourages completion, maximizes dwell time
    - Best for: Frameworks, step-by-step guides, data visualization
 
-**2. Native documents (PDFs): 24.42% engagement rate**
+**2. Native documents (PDFs): High engagement (historically 24.42%, likely inflated)**
+   - Note: The 24.42% figure is from 2025 studies that conflated PDF documents with multi-image carousels. Current carousel-specific data shows 1.92% engagement rate (still highest of all formats). PDF documents may still perform higher due to download value.
    - Great for frameworks, step-by-step content, detailed insights
    - Keeps users on platform (no external link penalty)
    - Downloadable = high perceived value
-   - Significant increase in engagement rate in 2026
    - Best for: Comprehensive guides, templates, detailed analyses
 
 **3. Video posts: 5.60% engagement rate**
-   - Optimal length: 90 seconds for engagement
+   - Optimal length: 60 seconds (2026 sweet spot, down from 90s)
+   - **Critical:** 30% minimum completion rate or video gets zero distribution
    - LinkedIn Live: 12-24x engagement vs standard posts
    - 85% watch without sound (captions essential)
-   - Vertical 4:5 aspect ratio (1080x1350) preferred over square
-   - First 3 seconds determine 70% of retention
-   - Note: Videos under 90 seconds optimal for engagement and dwell time balance
+   - **Vertical 9:16 (1080×1920)** now gets distribution boost (3-4x watch duration vs landscape). 4:5 still acceptable but deprioritized
+   - First 3 seconds determine 70% of retention — 3-second hook is critical
+   - Note: Overall video reach down 72% YoY — but good video is rewarded more than ever
    - Best for: Personal stories, quick insights, behind-the-scenes
    - See "Video Content Deep Dive" section below for comprehensive guidance
 
@@ -186,7 +187,7 @@ Algorithm prioritizes content that keeps users on platform longer.
 - Content that makes people pause and think
 
 **What doesn't improve dwell time despite engagement:**
-- Videos under 90 seconds (balance engagement with dwell time)
+- Videos under 60 seconds (balance engagement with completion rate)
 - Very short posts (quick reaction, quick scroll)
 - Polls (interaction but low time investment)
 
@@ -287,7 +288,7 @@ Immediate engagement in first hour is critical for triggering subsequent waves.
 **The Data Reality:**
 - Video posts get high impression counts
 - BUT: Engagement rates are often lower than text posts
-- Videos under 90 seconds optimal for balancing engagement and dwell time
+- Videos under 60 seconds optimal for balancing engagement and completion rate (30% minimum completion gate)
 - Algorithm prioritizes dwell time over impressions
 
 **What This Means:**
@@ -472,9 +473,9 @@ Video isn't the silver bullet many creators think it is. Text-based thought lead
 - Your comfort pace is usually 10-20% too slow
 
 **5. Length Optimization**
-- Ideal: 90 seconds (sweet spot for engagement vs dwell time)
-- Acceptable: 60-120 seconds
-- Avoid: <30 seconds (too shallow) or >2 minutes (retention drops)
+- Ideal: 60 seconds (2026 sweet spot — maximizes completion rate)
+- Acceptable: 30-90 seconds
+- Avoid: >90 seconds (completion rate drops, 30% minimum required for any distribution)
 
 **Editing tools by skill level:**
 
@@ -532,13 +533,14 @@ Video isn't the silver bullet many creators think it is. Text-based thought lead
 ### Technical Specifications
 
 **Video Format & Resolution:**
-- **Aspect ratio:** Vertical 4:5 (1080x1350) preferred for mobile optimization
-  - Vertical 4:5: 1080x1350px (optimal for 2026)
-  - Square 1:1: 1080x1080px (acceptable)
-  - If using 16:9: 1920x1080px minimum
+- **Aspect ratio:** Vertical 9:16 (1080x1920) now gets distribution boost in LinkedIn's immersive feed
+  - Vertical 9:16: 1080x1920px (optimal for 2026 — 3-4x watch duration vs landscape, 100% mobile viewport)
+  - Vertical 4:5: 1080x1350px (still acceptable)
+  - Square 1:1: 1080x1080px (deprioritized)
+  - If using 16:9: 1920x1080px minimum (only 25% of mobile viewport)
 - **File format:** MP4 (H.264 codec)
 - **Maximum file size:** 5GB
-- **Maximum length:** 10 minutes (but aim for 45-90 seconds)
+- **Maximum length:** 10 minutes (but aim for 30-60 seconds. 30% completion rate minimum or zero distribution)
 - **Frame rate:** 30fps standard, 60fps for smooth motion
 
 **Lighting:**
@@ -639,11 +641,11 @@ Before posting any video, verify:
 - [ ] Hook grabs attention in 3 seconds
 - [ ] Clear value delivered (lesson/insight)
 - [ ] Tight editing (no unnecessary seconds)
-- [ ] Length: 90 seconds optimal
+- [ ] Length: 60 seconds optimal (30% completion rate minimum)
 - [ ] Ends with engagement-focused CTA
 
 **Technical:**
-- [ ] Vertical 4:5 format (1080x1350) for maximum reach
+- [ ] Vertical 9:16 format (1080x1920) for maximum reach in immersive feed
 - [ ] Professional captions added
 - [ ] Audio quality clear and consistent
 - [ ] Thumbnail captures attention
@@ -657,7 +659,7 @@ Before posting any video, verify:
 - [ ] Complements overall content strategy
 - [ ] Doesn't include external links
 
-**Bottom Line on Video:** Use strategically when it genuinely adds value beyond text. Prioritize authenticity over production quality. Focus on 90 second videos that deliver concentrated insights. Always optimize for mobile-first consumption with vertical 4:5 format, captions and strong hooks.
+**Bottom Line on Video:** Use strategically when it genuinely adds value beyond text. Prioritize authenticity over production quality. Focus on 60-second videos that deliver concentrated insights. LinkedIn now requires 30% minimum completion rate for any distribution — shorter is safer. Always optimize for mobile-first consumption with vertical 9:16 format, captions, and 3-second hooks.
 
 
 ## Creator Mode Features (Available to All Users)