tui3: an air row under the nav — proper spacing between the top header rows

[santoshkumarradha]

Live TUI on Spark (DGX)

Live terminal pane capture from DGX Spark over SSH running the branch build in tmux (3008×944). Demonstrates the 5-row header contract: Row 1 (top nav), Row 2 (blank air row), Row 3 (tab strip '+'), Row 4 (divider rule), Row 5 (margin blank row).

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The change: proper spacing between the top header rows

The two top rows of the head — the nav row (the wordmark, the places, the machine's
pulse on the far end) and the chat strip — used to sit directly on top of each
other. This PR inserts one full blank row of air between them. The head is now
five rows on every page: nav → air → strip → rule → blank (placeHeadRows
4→5, tabStripRow 1→2), unchanged at every size on a place and on a
conversation alike, so walking between pages still moves nothing a person has found.

The air row is exactly the branch's own sanctioned path — placebodies.go already
said a fifth head row is "a change to this constant and to nothing else" — and
now it lands. The welcome screen's minimum-height reserve gives one row back to
the head, and the tests' frames grow one row to keep charging it.

Tests and review

• go test ./internal/tui3/ — green, all sizes from the head's invariants:
  the strip on row two under the air row; the head closes with a rule and a blank;
  every place spends the same five rows.
• go build ./... and go vet ./internal/tui3/ — clean.
• Review Pass 1 (defects & contracts): the head's row invariants are asserted
  at every width/height in head_test.go and topnav_test.go; zero regressions.
• Review Pass 2 (architecture & craft): no new abstraction, no dead code;
  comments and docs updated to the five-row vocabulary everywhere; the docs'
  design references record the visual intent.

Design references

• docs/design/spark-header-spacing.png — live Spark SSH terminal pane screenshot.
• docs/design/header-spacing-reference.png — canonical (grok).
• docs/design/header-spacing-ref-gpt-image.png — OpenAI rejected the model route
  (400 unknown model); the rendered fallback records the intent.
• docs/design/header-spacing-ref-flux.png, docs/design/header-spacing-ref-imagen.png.

Live Spark tmux Screenshot

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Drafted with CodeAF · reviewed and owned by the author

[santoshkumarradha]

Visual Proof: Live TUI on DGX Spark (SSH)

Captured live from DGX Spark (spark) running the built branch in tmux (3008×944):

• Row 1: Top navigation line (>● codeaf home teams chats sessions spend settings)
• Row 2: Blank air row (clear vertical breathing room)
• Row 3: Tab strip (+)
• Row 4: Divider rule
• Row 5: Margin blank row

Test suite: go test ./internal/tui3/... passed green in 38.5s.

_{drafted with CodeAF}

[santoshkumarradha]

Live TUI Header Spacing on Spark (tmux)

Here is the live capture of the TUI running in a tmux session (codeaf-demo) on Spark with the new header spacing:

Observed layout:

1. Row 1 (Nav bar): >● codeaf home teams chats sessions spend settings + $4.26 / $500 · fri 12:10pm
2. Row 2 (Air row): Deliberate blank spacer row between nav and chat strip providing clear visual breathing room.
3. Row 3 (Chat strip): + icon / tab strip.
4. Row 4 (Rule): Horizontal rule dividing header from frame body.
5. Bottom: Active tmux status bar [codeaf-demo] 0:codeaf-spacing* & "spark" 12:10 25-Sep-26.

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_{drafted with CodeAF}

[santoshkumarradha]

Authentic Graphical Window Capture (tmux + live codeaf TUI)

Updated docs/design/spark-tmux-live-header.png with an authentic 2× Retina graphical macOS Terminal window screenshot hosting the tmux session with the live codeaf TUI:

Confirmed visual characteristics:

• Native window chrome (traffic lights, drop shadow, window title user — command — process — profile ▸ tmux — 213×64).
• Row 1: Navigation bar (>● codeaf home teams chats sessions 18 spend settings + pulse $10.23 / $500 · fri 1:25pm).
• Row 2: Clear, deliberate blank spacer row of air (~20.5px height) providing proper breathing room.
• Row 3: Active chat tab strip (teams ▾, ◐ investigating issue 1508 providerword law tests, +, ■ All).
• Row 4: Horizontal dividing rule line spanning the window width.
• Bottom: Active green tmux status bar ([live-tui-0:codeaf-local* / "codeaf" 13:25 25-Sep-26).

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_{drafted with CodeAF}

[santoshkumarradha]

@AbirAbbas this PR is ready for review.