docs: note start-of-week in design-guidelines, codebase-summary, deployment-guide

- design-guidelines: heatmap row order + productive-weekday bar order now derive from Profile.WeekStart
- codebase-summary: list new weekday_start_test.go cases + TestParseWeekday
- deployment-guide: mention start_of_week as an optional action input in the workflow template

docs/codebase-summary.md

@@ -31,7 +31,7 @@ ghstats/
 │   │   ├── productive.go                # productive-time (+ all-time)
 │   │   ├── productive_weekday.go        # productive-weekday (+ all-time)
 │   │   ├── contributions.go             # contributions (+ all-time)
-│   │   ├── contributions_heatmap.go     # contributions-heatmap (7×53 calendar grid)
+│   │   ├── contributions_heatmap.go     # contributions-heatmap (7×53 calendar grid; row 0 = Profile.WeekStart)
 │   │   ├── contributions_by_year.go     # contributions-by-year bar chart
 │   │   ├── streak.go                    # streak (current/longest/active days)
 │   │   ├── top_starred_repos.go         # top-starred-repos bar list
@@ -110,8 +110,9 @@ commitHistoryQuery ──► Productive + Weekday + CommitsByLanguage (+ AllTime
 ## Test coverage
 
 - `internal/card/card_test.go` — `RenderAll` produces 15 valid SVGs; XML escape through real render pipeline; `formatInt` cases; `TestDonutSingleSlice` / `TestDonutEmpty` (donut edge cases); `TestCardsFitFrame` (renders every card against an adversarial profile and asserts text + coordinates stay in the 340×200 frame); `TestFitTitleFontSize` (pins the auto-shrink table for every real title); `TestNiceTicksCoversMax` (guards the `yMax ≥ dataMax` invariant so bars can't overflow chartH).
+- `internal/card/weekday_start_test.go` — `TestPadToWeekGridRotatesByWeekStart` (leading pad matches configured start day), `TestRenderWeekdayRespectsWeekStart` (bar order rotates with `WeekStart`), `TestRenderHeatmapLabelsRespectWeekStart` (heatmap row labels rotate accordingly).
 - `internal/github/profile_test.go` — `sortLangStats` ordering and tiebreak.
-- `main_test.go` — `TestUTCOffsetLabel` covers UTC, Asia/Saigon, half-hour (Kolkata), quarter-hour (Kathmandu) zones.
+- `main_test.go` — `TestUTCOffsetLabel` covers UTC, Asia/Saigon, half-hour (Kolkata), quarter-hour (Kathmandu) zones. `TestParseWeekday` covers the `-start-of-week` input parsing.
 
 No network-touching tests; real runs verified via `-token` + local build.
 

docs/deployment-guide.md

@@ -30,6 +30,7 @@ jobs:
           token: ${{ secrets.GHSTATS_TOKEN }}
           themes: dracula,github_dark,tokyonight
           tz: Asia/Saigon
+          # start_of_week: monday   # optional; default sunday — rotates heatmap rows + weekday bars
           include_forks: "false"
           include_private: "false"
           commit_changes: "true"

docs/design-guidelines.md

@@ -72,6 +72,7 @@ When there's **exactly one slice** (one language at 100%), the renderer emits tw
 | Axis caption | "hour of day" bottom-center on productive-time; weekday / by-year omit the caption since the x labels are self-describing |
 | Title format | `Commits by Hour (<window>, UTC±H[:MM])` / `Commits by Weekday (<window>)` — weekday drops the UTC so the title always fits at 15 px / `Contributions by Year` |
 | Hover | `<title>HH:00 — N commits</title>` / `<title>Mon — N commits</title>` / `<title>YYYY — N commits</title>` |
+| Bar order | `productive-weekday`: position 0 = `Profile.WeekStart` (set via `-start-of-week`, default Sunday); remaining bars rotate forward `(WeekStart+i) % 7`. Peak highlight tracks the drawn position so it stays aligned with the visible tallest bar. |
 
 ## Heatmap card (contributions-heatmap)
 
@@ -81,7 +82,8 @@ When there's **exactly one slice** (one language at 100%), the renderer emits tw
 | Cell size | 8 × 8 px square, 1 px gap |
 | Grid geometry | `leftPad 30`, `topPadA 45` (top half), `halfGap 13`, `topPadB 120`. Each half is 7 × 9 − 1 = 62 px tall. Grid bottom at y=182 leaves 18 px for the frame border. |
 | Cell colour | 5-bucket ramp `mixHex(Background, Accent, k/4)` for `k ∈ 0..4` — no dedicated ramp field on the theme schema |
-| Weekday labels | Mon / Wed / Fri only, right-anchored in the `leftPad` gutter |
+| Weekday labels | Every other row (positions 1, 3, 5), right-anchored in the `leftPad` gutter. Label text is `weekdayShort[(int(WeekStart)+i) % 7]`, so Sunday-start renders Mon/Wed/Fri; Monday-start renders Tue/Thu/Sat. |
+| Row order | Row 0 = `Profile.WeekStart` (`-start-of-week` flag; default `time.Sunday` matches GitHub's own calendar). `padToWeekGrid` rotates the leading blank pad to match. |
 | Month labels | Printed above the first week where a 1st-of-month day falls; skipped when `x > width − 20` so `Dec` / `Apr` can't spill past the frame |
 | Legend | "Less ▢▢▢▢▢ More" bottom-right |
 | Hover | `<title>YYYY-MM-DD — N</title>` per cell |