diff --git a/.surface b/.surface
index 935e43236..1b6b8238d 100644
--- a/.surface
+++ b/.surface
@@ -334,11 +334,15 @@ ARG basecamp project delete 00 <id>
 ARG basecamp project show 00 <id>
 ARG basecamp project trash 00 <id>
 ARG basecamp project update 00 <id>
+ARG basecamp project wallpaper mode 00 <fill|tile>
+ARG basecamp project wallpaper set 00 <file>
 ARG basecamp projects create 00 <name>
 ARG basecamp projects delete 00 <id>
 ARG basecamp projects show 00 <id>
 ARG basecamp projects trash 00 <id>
 ARG basecamp projects update 00 <id>
+ARG basecamp projects wallpaper mode 00 <fill|tile>
+ARG basecamp projects wallpaper set 00 <file>
 ARG basecamp recordings 00 [type]
 ARG basecamp recordings active 00 <id|url>
 ARG basecamp recordings archive 00 <id|url>
@@ -1028,6 +1032,10 @@ CMD basecamp project list
 CMD basecamp project show
 CMD basecamp project trash
 CMD basecamp project update
+CMD basecamp project wallpaper
+CMD basecamp project wallpaper mode
+CMD basecamp project wallpaper remove
+CMD basecamp project wallpaper set
 CMD basecamp projects
 CMD basecamp projects create
 CMD basecamp projects delete
@@ -1035,6 +1043,10 @@ CMD basecamp projects list
 CMD basecamp projects show
 CMD basecamp projects trash
 CMD basecamp projects update
+CMD basecamp projects wallpaper
+CMD basecamp projects wallpaper mode
+CMD basecamp projects wallpaper remove
+CMD basecamp projects wallpaper set
 CMD basecamp recordings
 CMD basecamp recordings active
 CMD basecamp recordings archive
@@ -13236,6 +13248,91 @@ FLAG basecamp project update --stats type=bool
 FLAG basecamp project update --styled type=bool
 FLAG basecamp project update --todolist type=string
 FLAG basecamp project update --verbose type=count
+FLAG basecamp project wallpaper --account type=string
+FLAG basecamp project wallpaper --agent type=bool
+FLAG basecamp project wallpaper --cache-dir type=string
+FLAG basecamp project wallpaper --count type=bool
+FLAG basecamp project wallpaper --help type=bool
+FLAG basecamp project wallpaper --hints type=bool
+FLAG basecamp project wallpaper --ids-only type=bool
+FLAG basecamp project wallpaper --in type=string
+FLAG basecamp project wallpaper --jq type=string
+FLAG basecamp project wallpaper --json type=bool
+FLAG basecamp project wallpaper --markdown type=bool
+FLAG basecamp project wallpaper --md type=bool
+FLAG basecamp project wallpaper --no-hints type=bool
+FLAG basecamp project wallpaper --no-stats type=bool
+FLAG basecamp project wallpaper --profile type=string
+FLAG basecamp project wallpaper --project type=string
+FLAG basecamp project wallpaper --quiet type=bool
+FLAG basecamp project wallpaper --stats type=bool
+FLAG basecamp project wallpaper --styled type=bool
+FLAG basecamp project wallpaper --todolist type=string
+FLAG basecamp project wallpaper --verbose type=count
+FLAG basecamp project wallpaper mode --account type=string
+FLAG basecamp project wallpaper mode --agent type=bool
+FLAG basecamp project wallpaper mode --cache-dir type=string
+FLAG basecamp project wallpaper mode --count type=bool
+FLAG basecamp project wallpaper mode --help type=bool
+FLAG basecamp project wallpaper mode --hints type=bool
+FLAG basecamp project wallpaper mode --ids-only type=bool
+FLAG basecamp project wallpaper mode --in type=string
+FLAG basecamp project wallpaper mode --jq type=string
+FLAG basecamp project wallpaper mode --json type=bool
+FLAG basecamp project wallpaper mode --markdown type=bool
+FLAG basecamp project wallpaper mode --md type=bool
+FLAG basecamp project wallpaper mode --no-hints type=bool
+FLAG basecamp project wallpaper mode --no-stats type=bool
+FLAG basecamp project wallpaper mode --profile type=string
+FLAG basecamp project wallpaper mode --project type=string
+FLAG basecamp project wallpaper mode --quiet type=bool
+FLAG basecamp project wallpaper mode --stats type=bool
+FLAG basecamp project wallpaper mode --styled type=bool
+FLAG basecamp project wallpaper mode --todolist type=string
+FLAG basecamp project wallpaper mode --verbose type=count
+FLAG basecamp project wallpaper remove --account type=string
+FLAG basecamp project wallpaper remove --agent type=bool
+FLAG basecamp project wallpaper remove --cache-dir type=string
+FLAG basecamp project wallpaper remove --count type=bool
+FLAG basecamp project wallpaper remove --help type=bool
+FLAG basecamp project wallpaper remove --hints type=bool
+FLAG basecamp project wallpaper remove --ids-only type=bool
+FLAG basecamp project wallpaper remove --in type=string
+FLAG basecamp project wallpaper remove --jq type=string
+FLAG basecamp project wallpaper remove --json type=bool
+FLAG basecamp project wallpaper remove --markdown type=bool
+FLAG basecamp project wallpaper remove --md type=bool
+FLAG basecamp project wallpaper remove --no-hints type=bool
+FLAG basecamp project wallpaper remove --no-stats type=bool
+FLAG basecamp project wallpaper remove --profile type=string
+FLAG basecamp project wallpaper remove --project type=string
+FLAG basecamp project wallpaper remove --quiet type=bool
+FLAG basecamp project wallpaper remove --stats type=bool
+FLAG basecamp project wallpaper remove --styled type=bool
+FLAG basecamp project wallpaper remove --todolist type=string
+FLAG basecamp project wallpaper remove --verbose type=count
+FLAG basecamp project wallpaper set --account type=string
+FLAG basecamp project wallpaper set --agent type=bool
+FLAG basecamp project wallpaper set --cache-dir type=string
+FLAG basecamp project wallpaper set --count type=bool
+FLAG basecamp project wallpaper set --help type=bool
+FLAG basecamp project wallpaper set --hints type=bool
+FLAG basecamp project wallpaper set --ids-only type=bool
+FLAG basecamp project wallpaper set --in type=string
+FLAG basecamp project wallpaper set --jq type=string
+FLAG basecamp project wallpaper set --json type=bool
+FLAG basecamp project wallpaper set --markdown type=bool
+FLAG basecamp project wallpaper set --md type=bool
+FLAG basecamp project wallpaper set --mode type=string
+FLAG basecamp project wallpaper set --no-hints type=bool
+FLAG basecamp project wallpaper set --no-stats type=bool
+FLAG basecamp project wallpaper set --profile type=string
+FLAG basecamp project wallpaper set --project type=string
+FLAG basecamp project wallpaper set --quiet type=bool
+FLAG basecamp project wallpaper set --stats type=bool
+FLAG basecamp project wallpaper set --styled type=bool
+FLAG basecamp project wallpaper set --todolist type=string
+FLAG basecamp project wallpaper set --verbose type=count
 FLAG basecamp projects --account type=string
 FLAG basecamp projects --agent type=bool
 FLAG basecamp projects --cache-dir type=string
@@ -13393,6 +13490,91 @@ FLAG basecamp projects update --stats type=bool
 FLAG basecamp projects update --styled type=bool
 FLAG basecamp projects update --todolist type=string
 FLAG basecamp projects update --verbose type=count
+FLAG basecamp projects wallpaper --account type=string
+FLAG basecamp projects wallpaper --agent type=bool
+FLAG basecamp projects wallpaper --cache-dir type=string
+FLAG basecamp projects wallpaper --count type=bool
+FLAG basecamp projects wallpaper --help type=bool
+FLAG basecamp projects wallpaper --hints type=bool
+FLAG basecamp projects wallpaper --ids-only type=bool
+FLAG basecamp projects wallpaper --in type=string
+FLAG basecamp projects wallpaper --jq type=string
+FLAG basecamp projects wallpaper --json type=bool
+FLAG basecamp projects wallpaper --markdown type=bool
+FLAG basecamp projects wallpaper --md type=bool
+FLAG basecamp projects wallpaper --no-hints type=bool
+FLAG basecamp projects wallpaper --no-stats type=bool
+FLAG basecamp projects wallpaper --profile type=string
+FLAG basecamp projects wallpaper --project type=string
+FLAG basecamp projects wallpaper --quiet type=bool
+FLAG basecamp projects wallpaper --stats type=bool
+FLAG basecamp projects wallpaper --styled type=bool
+FLAG basecamp projects wallpaper --todolist type=string
+FLAG basecamp projects wallpaper --verbose type=count
+FLAG basecamp projects wallpaper mode --account type=string
+FLAG basecamp projects wallpaper mode --agent type=bool
+FLAG basecamp projects wallpaper mode --cache-dir type=string
+FLAG basecamp projects wallpaper mode --count type=bool
+FLAG basecamp projects wallpaper mode --help type=bool
+FLAG basecamp projects wallpaper mode --hints type=bool
+FLAG basecamp projects wallpaper mode --ids-only type=bool
+FLAG basecamp projects wallpaper mode --in type=string
+FLAG basecamp projects wallpaper mode --jq type=string
+FLAG basecamp projects wallpaper mode --json type=bool
+FLAG basecamp projects wallpaper mode --markdown type=bool
+FLAG basecamp projects wallpaper mode --md type=bool
+FLAG basecamp projects wallpaper mode --no-hints type=bool
+FLAG basecamp projects wallpaper mode --no-stats type=bool
+FLAG basecamp projects wallpaper mode --profile type=string
+FLAG basecamp projects wallpaper mode --project type=string
+FLAG basecamp projects wallpaper mode --quiet type=bool
+FLAG basecamp projects wallpaper mode --stats type=bool
+FLAG basecamp projects wallpaper mode --styled type=bool
+FLAG basecamp projects wallpaper mode --todolist type=string
+FLAG basecamp projects wallpaper mode --verbose type=count
+FLAG basecamp projects wallpaper remove --account type=string
+FLAG basecamp projects wallpaper remove --agent type=bool
+FLAG basecamp projects wallpaper remove --cache-dir type=string
+FLAG basecamp projects wallpaper remove --count type=bool
+FLAG basecamp projects wallpaper remove --help type=bool
+FLAG basecamp projects wallpaper remove --hints type=bool
+FLAG basecamp projects wallpaper remove --ids-only type=bool
+FLAG basecamp projects wallpaper remove --in type=string
+FLAG basecamp projects wallpaper remove --jq type=string
+FLAG basecamp projects wallpaper remove --json type=bool
+FLAG basecamp projects wallpaper remove --markdown type=bool
+FLAG basecamp projects wallpaper remove --md type=bool
+FLAG basecamp projects wallpaper remove --no-hints type=bool
+FLAG basecamp projects wallpaper remove --no-stats type=bool
+FLAG basecamp projects wallpaper remove --profile type=string
+FLAG basecamp projects wallpaper remove --project type=string
+FLAG basecamp projects wallpaper remove --quiet type=bool
+FLAG basecamp projects wallpaper remove --stats type=bool
+FLAG basecamp projects wallpaper remove --styled type=bool
+FLAG basecamp projects wallpaper remove --todolist type=string
+FLAG basecamp projects wallpaper remove --verbose type=count
+FLAG basecamp projects wallpaper set --account type=string
+FLAG basecamp projects wallpaper set --agent type=bool
+FLAG basecamp projects wallpaper set --cache-dir type=string
+FLAG basecamp projects wallpaper set --count type=bool
+FLAG basecamp projects wallpaper set --help type=bool
+FLAG basecamp projects wallpaper set --hints type=bool
+FLAG basecamp projects wallpaper set --ids-only type=bool
+FLAG basecamp projects wallpaper set --in type=string
+FLAG basecamp projects wallpaper set --jq type=string
+FLAG basecamp projects wallpaper set --json type=bool
+FLAG basecamp projects wallpaper set --markdown type=bool
+FLAG basecamp projects wallpaper set --md type=bool
+FLAG basecamp projects wallpaper set --mode type=string
+FLAG basecamp projects wallpaper set --no-hints type=bool
+FLAG basecamp projects wallpaper set --no-stats type=bool
+FLAG basecamp projects wallpaper set --profile type=string
+FLAG basecamp projects wallpaper set --project type=string
+FLAG basecamp projects wallpaper set --quiet type=bool
+FLAG basecamp projects wallpaper set --stats type=bool
+FLAG basecamp projects wallpaper set --styled type=bool
+FLAG basecamp projects wallpaper set --todolist type=string
+FLAG basecamp projects wallpaper set --verbose type=count
 FLAG basecamp recordings --account type=string
 FLAG basecamp recordings --agent type=bool
 FLAG basecamp recordings --all type=bool
@@ -19873,6 +20055,10 @@ SUB basecamp project list
 SUB basecamp project show
 SUB basecamp project trash
 SUB basecamp project update
+SUB basecamp project wallpaper
+SUB basecamp project wallpaper mode
+SUB basecamp project wallpaper remove
+SUB basecamp project wallpaper set
 SUB basecamp projects
 SUB basecamp projects create
 SUB basecamp projects delete
@@ -19880,6 +20066,10 @@ SUB basecamp projects list
 SUB basecamp projects show
 SUB basecamp projects trash
 SUB basecamp projects update
+SUB basecamp projects wallpaper
+SUB basecamp projects wallpaper mode
+SUB basecamp projects wallpaper remove
+SUB basecamp projects wallpaper set
 SUB basecamp recordings
 SUB basecamp recordings active
 SUB basecamp recordings archive
diff --git a/API-COVERAGE.md b/API-COVERAGE.md
index 5a8bc5452..bb0d99b41 100644
--- a/API-COVERAGE.md
+++ b/API-COVERAGE.md
@@ -6,12 +6,16 @@ Coverage of Basecamp 3 API endpoints. Source: [bc3-api/sections](https://github.
 
 | Status | Sections | Endpoints |
 |--------|----------|-----------|
-| ✅ Implemented | 55 | 211 |
+| ✅ Implemented | 55 | 213 |
 | ⚠️ Blocked | 0 | 0 |
 | ⏭️ Out of scope | 4 | 12 |
-| **Total tracked** | **59** | **223** |
+| **Total tracked** | **59** | **225** |
 
-**211 of 211 tracked in-scope endpoints.** Spotlighting a recording on its
+**213 of 213 tracked in-scope endpoints.** Uploading and removing a project's
+wallpaper (`PUT`/`DELETE /projects/:id/wallpaper.json`, added by
+[bc3#14062](https://github.com/basecamp/bc3/pull/14062) and shipped in
+[SDK v0.28.0](https://github.com/basecamp/basecamp-sdk/releases/tag/v0.28.0))
+land as `projects wallpaper`. Spotlighting a recording on its
 project or template home page (`POST`/`DELETE /recordings/:id/spotlight.json`,
 SDK v0.27.0) lands as `spotlight` and `unspotlight`. The two embed endpoints bc3 documents
 in `embeds.md` — `POST /embeds.json` and `GET /embeds/:sgid.json` — land as
@@ -201,6 +205,7 @@ cannot faithfully cover at least one endpoint for a reason outside the CLI. A
 |---------|-----------|-------------|--------|-------|----------|-------|
 | **Core** |
 | projects | 9 | `projects` | ✅ | BC4 | - | list, show, create, update, delete |
+| projects (wallpaper) | 2 | `projects wallpaper` | ✅ | BC5 | - | set (`PUT /projects/:id/wallpaper.json`, multipart `wallpaper` with an optional `mode`), remove (`DELETE` on the same route; 204 with or without a wallpaper). `mode` sends `wallpaper_mode` through the existing `PUT /projects/:id.json`, with the current name the SDK requires. PNG, JPEG, GIF, WebP, AVIF, HEIF or HEIC up to 10 MB, checked before the upload using a local MIME hint; the server applies its shared image validations. People and personal assistants follow project-edit permissions; shared agents are refused with 403. Project JSON carries `wallpaper {url, mode}` when one is attached, so `projects show` shows it. Project-scoped via `--in`/`--project` |
 | todos | 12 | `todos`, `todo`, `done`, `reopen` | ✅ | BC4 | - | list, show, create, update, complete, uncomplete, position (BC5: `steps` shown on `todos show`, plus `subtasks_count`/`subtasks_completed_count`/`subtasks_url`; edit via `subtasks`). `todos create --loose` creates on the to-do set, outside any list |
 | subtasks | 8 | `subtasks` | ✅ | BC5 | - | list (`GET /recordings/:id/subtasks.json`, paginated), show, create (`POST` on the same list route), update (partial; `--no-due`/`--no-assignees` clear), complete/uncomplete (`POST`/`DELETE /subtasks/:id/completion.json`), move (`PUT /subtasks/:id/position.json`, 1-based), delete. Account-scoped flat routes (bc3#12659), so no `--in`. Parents are to-dos and cards only. Same `Kanban::Step` records as `card_table_steps` |
 | todolists | 9 | `todolists` | ✅ | BC4 | - | list, show, create, update, position |
diff --git a/e2e/projects.bats b/e2e/projects.bats
new file mode 100644
index 000000000..973aeba72
--- /dev/null
+++ b/e2e/projects.bats
@@ -0,0 +1,93 @@
+#!/usr/bin/env bats
+# projects.bats - Test projects command input handling
+
+load test_helper
+
+
+# Help
+
+@test "projects wallpaper without subcommand shows help" {
+  run basecamp projects wallpaper
+  assert_success
+  assert_output_contains "COMMANDS"
+  assert_output_contains "set"
+  assert_output_contains "mode"
+  assert_output_contains "remove"
+}
+
+@test "projects wallpaper set help names the formats and the size cap" {
+  run basecamp projects wallpaper set --help
+  assert_success
+  assert_output_contains "PNG, JPEG, GIF, WebP, AVIF, HEIF, or HEIC files up to 10 MB"
+}
+
+
+# Input errors that need no network
+
+@test "projects wallpaper set without a file shows error" {
+  create_credentials
+  create_global_config '{"account_id": 99999, "project_id": 123}'
+
+  run basecamp projects wallpaper set
+  assert_failure
+  assert_json_value '.error' '<file> required'
+  assert_json_value '.code' 'usage'
+}
+
+@test "projects wallpaper set refuses an SVG" {
+  create_credentials
+  create_global_config '{"account_id": 99999, "project_id": 123}'
+  printf '<svg></svg>' > image.svg
+
+  run basecamp projects wallpaper set image.svg
+  assert_failure
+  assert_json_value '.error' 'image.svg: unsupported image type image/svg+xml (use PNG, JPEG, GIF, WebP, AVIF, HEIF, or HEIC)'
+  assert_json_value '.code' 'usage'
+}
+
+@test "projects wallpaper set refuses a file over 10 MB" {
+  create_credentials
+  create_global_config '{"account_id": 99999, "project_id": 123}'
+  dd if=/dev/zero of=big.png bs=1 count=1 seek=10485760 2>/dev/null
+
+  run basecamp projects wallpaper set big.png
+  assert_failure
+  assert_json_value '.error' 'big.png exceeds maximum wallpaper size of 10 MB'
+}
+
+@test "projects wallpaper set refuses an unknown --mode" {
+  create_credentials
+  create_global_config '{"account_id": 99999, "project_id": 123}'
+  printf '\x89PNG\r\n\x1a\n' > skyline.png
+
+  run basecamp projects wallpaper set skyline.png --mode stretch
+  assert_failure
+  assert_json_value '.error' 'unknown wallpaper mode "stretch"'
+  assert_json_value '.hint' 'Use fill or tile'
+}
+
+@test "projects wallpaper mode without a mode shows error" {
+  create_credentials
+  create_global_config '{"account_id": 99999, "project_id": 123}'
+
+  run basecamp projects wallpaper mode
+  assert_failure
+  assert_json_value '.error' '<fill|tile> required'
+}
+
+@test "projects wallpaper mode refuses an unknown mode" {
+  create_credentials
+  create_global_config '{"account_id": 99999, "project_id": 123}'
+
+  run basecamp projects wallpaper mode stretch
+  assert_failure
+  assert_json_value '.error' 'unknown wallpaper mode "stretch"'
+}
+
+@test "projects wallpaper remove takes no arguments" {
+  create_credentials
+  create_global_config '{"account_id": 99999, "project_id": 123}'
+
+  run basecamp projects wallpaper remove skyline.png
+  assert_failure
+}
diff --git a/e2e/smoke/smoke_projects_write.bats b/e2e/smoke/smoke_projects_write.bats
index aa7fea558..c9a9fe784 100644
--- a/e2e/smoke/smoke_projects_write.bats
+++ b/e2e/smoke/smoke_projects_write.bats
@@ -30,6 +30,42 @@ setup_file() {
   assert_json_value '.ok' 'true'
 }
 
+@test "projects wallpaper set uploads a tiled wallpaper" {
+  local id_file="$BATS_FILE_TMPDIR/created_project_id"
+  [[ -f "$id_file" ]] || mark_unverifiable "No project created in prior test"
+  local proj_id
+  proj_id=$(<"$id_file")
+  local png="$BATS_FILE_TMPDIR/wallpaper.png"
+  printf '%s' 'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNkYPhfDwAChwGA60e6kgAAAABJRU5ErkJggg==' |
+    base64 -d > "$png"
+
+  run_smoke basecamp projects wallpaper set "$png" --mode tile --project "$proj_id" --json
+  assert_success
+  assert_json_value '.data.wallpaper.mode' 'tile'
+  assert_json_not_null '.data.wallpaper.url'
+  touch "$BATS_FILE_TMPDIR/wallpaper_set"
+}
+
+@test "projects wallpaper mode changes the layout" {
+  [[ -f "$BATS_FILE_TMPDIR/wallpaper_set" ]] || mark_unverifiable "No wallpaper set in prior test"
+  local proj_id
+  proj_id=$(<"$BATS_FILE_TMPDIR/created_project_id")
+
+  run_smoke basecamp projects wallpaper mode fill --project "$proj_id" --json
+  assert_success
+  assert_json_value '.data.wallpaper.mode' 'fill'
+}
+
+@test "projects wallpaper remove clears the wallpaper" {
+  [[ -f "$BATS_FILE_TMPDIR/wallpaper_set" ]] || mark_unverifiable "No wallpaper set in prior test"
+  local proj_id
+  proj_id=$(<"$BATS_FILE_TMPDIR/created_project_id")
+
+  run_smoke basecamp projects wallpaper remove --project "$proj_id" --json
+  assert_success
+  assert_json_value '.data.wallpaper' 'null'
+}
+
 @test "projects delete deletes a project" {
   local id_file="$BATS_FILE_TMPDIR/created_project_id"
   [[ -f "$id_file" ]] || mark_unverifiable "No project created in prior test"
diff --git a/go.mod b/go.mod
index 6ad7e9f21..9cdd2fbc6 100644
--- a/go.mod
+++ b/go.mod
@@ -8,7 +8,7 @@ require (
 	charm.land/bubbles/v2 v2.2.1
 	charm.land/bubbletea/v2 v2.1.0
 	charm.land/lipgloss/v2 v2.0.6
-	github.com/basecamp/basecamp-sdk/go v0.27.1-0.20261022230746-63115e7978c9
+	github.com/basecamp/basecamp-sdk/go v0.28.0
 	github.com/basecamp/cli v0.2.2-0.20261023171439-c9bce8206df9
 	github.com/basecamp/mcp v0.0.0-20260828100356-2d6f44b51e9d
 	github.com/basecamp/surfguard/go v0.1.0
diff --git a/go.sum b/go.sum
index bf81fac46..236448fc9 100644
--- a/go.sum
+++ b/go.sum
@@ -89,8 +89,8 @@ github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuP
 github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
 github.com/basecamp/actioncable-go v1.2.0 h1:t0MxlfMTcmaGXZ5ztgKRs7ZiY1MwXtBRwSSSAh1ofVg=
 github.com/basecamp/actioncable-go v1.2.0/go.mod h1:ezaV5z1GXQAsqyejqTs6wCFl2D8Wj+COLQkHc/kwoRs=
-github.com/basecamp/basecamp-sdk/go v0.27.1-0.20261022230746-63115e7978c9 h1:ZcW7c/cnQTgFkNHMcnkxPqHIko2d0v2MrOgyykBrOj0=
-github.com/basecamp/basecamp-sdk/go v0.27.1-0.20261022230746-63115e7978c9/go.mod h1:mUm/MQGMyg1E1cddyxdG7tQHiq0NsYee2zUeAUT5VjU=
+github.com/basecamp/basecamp-sdk/go v0.28.0 h1:OwMD/mg/2QvVGtvSRkMraCOjrYVQk3Dgz/IJPPA6P90=
+github.com/basecamp/basecamp-sdk/go v0.28.0/go.mod h1:mUm/MQGMyg1E1cddyxdG7tQHiq0NsYee2zUeAUT5VjU=
 github.com/basecamp/cli v0.2.2-0.20261023171439-c9bce8206df9 h1:3NfGs+zx23Tp6cf+97+UewrJHlzZMLzmvEXOmOJyQAk=
 github.com/basecamp/cli v0.2.2-0.20261023171439-c9bce8206df9/go.mod h1:iTBTaWvsPEFIcZfkxQHEfISyJ6sZ7036K6bNx0RY3EE=
 github.com/basecamp/mcp v0.0.0-20260828100356-2d6f44b51e9d h1:zEQVGq1x1nhKMZ2TudFAcSJ32CHT8richI1vQakIKz4=
diff --git a/internal/commands/commands.go b/internal/commands/commands.go
index ca6c799cc..7936ac2d7 100644
--- a/internal/commands/commands.go
+++ b/internal/commands/commands.go
@@ -34,7 +34,7 @@ func CommandCategories() []CommandCategory {
 		{
 			Name: "Core Commands",
 			Commands: []CommandInfo{
-				{Name: "projects", Category: "core", Description: "Manage projects", Actions: []string{"list", "show", "create", "update", "delete"}},
+				{Name: "projects", Category: "core", Description: "Manage projects", Actions: []string{"list", "show", "create", "update", "delete", "wallpaper"}},
 				{Name: "todos", Category: "core", Description: "Manage to-dos", Actions: []string{"list", "show", "create", "update", "complete", "uncomplete", "position", "trash", "archive", "restore"}},
 				{Name: "subtasks", Category: "core", Description: "Manage subtasks on to-dos and cards", Actions: []string{"list", "show", "create", "update", "complete", "uncomplete", "move", "delete"}},
 				{Name: "todolists", Category: "core", Description: "Manage to-do lists", Actions: []string{"list", "show", "create", "update", "position", "trash", "archive", "restore"}},
diff --git a/internal/commands/projects.go b/internal/commands/projects.go
index 4cf270ddc..015066dd9 100644
--- a/internal/commands/projects.go
+++ b/internal/commands/projects.go
@@ -3,6 +3,8 @@ package commands
 import (
 	"errors"
 	"fmt"
+	"os"
+	"path/filepath"
 	"slices"
 	"sort"
 	"strconv"
@@ -15,6 +17,7 @@ import (
 	"github.com/basecamp/basecamp-cli/internal/appctx"
 	"github.com/basecamp/basecamp-cli/internal/completion"
 	"github.com/basecamp/basecamp-cli/internal/output"
+	"github.com/basecamp/basecamp-cli/internal/richtext"
 )
 
 // NewProjectsCmd creates the projects command group.
@@ -37,6 +40,7 @@ func NewProjectsCmd() *cobra.Command {
 		newProjectsCreateCmd(),
 		newProjectsUpdateCmd(),
 		newProjectsDeleteCmd(),
+		newProjectsWallpaperCmd(),
 	)
 
 	return cmd
@@ -427,6 +431,286 @@ func newProjectsDeleteCmd() *cobra.Command {
 	}
 }
 
+// wallpaperFormats match the server's shared image validation, not the narrower web picker.
+var wallpaperFormats = []struct{ mime, name string }{
+	{"image/png", "PNG"},
+	{"image/jpeg", "JPEG"},
+	{"image/gif", "GIF"},
+	{"image/webp", "WebP"},
+	{"image/avif", "AVIF"},
+	{"image/heif", "HEIF"},
+	{"image/heic", "HEIC"},
+}
+
+const maxWallpaperMB = 10
+
+var wallpaperModes = []string{"fill", "tile"}
+
+func wallpaperAgentNotes() map[string]string {
+	return map[string]string{"agent_notes": "People and personal assistants follow project-edit permissions; shared agents are refused (403)\n.data.wallpaper is {url, mode}, absent when there is none; url requires authentication and redirects to the image"}
+}
+
+func newProjectsWallpaperCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:         "wallpaper",
+		Short:       "Manage a project's wallpaper",
+		Annotations: wallpaperAgentNotes(),
+		Long: `Set, lay out, or remove a project's wallpaper.
+
+The project comes from --project (or --in), then the configured default.
+People and personal assistants with project-edit permissions can change its wallpaper.
+Shared agents are refused.`,
+		Example: `  $ basecamp projects wallpaper set skyline.jpg --mode fill --project 12345
+  $ basecamp projects wallpaper mode tile --project 12345
+  $ basecamp projects wallpaper remove --project 12345`,
+	}
+
+	cmd.AddCommand(
+		newProjectsWallpaperSetCmd(),
+		newProjectsWallpaperModeCmd(),
+		newProjectsWallpaperRemoveCmd(),
+	)
+
+	return cmd
+}
+
+func newProjectsWallpaperSetCmd() *cobra.Command {
+	var mode string
+
+	cmd := &cobra.Command{
+		Use:         "set <file>",
+		Annotations: wallpaperAgentNotes(),
+		Short:       "Upload or replace a project's wallpaper",
+		Long: fmt.Sprintf(`Upload or replace the project's wallpaper.
+
+Accepts %s files up to %d MB.
+--mode lays the image out (%s); without it the project keeps
+its current mode.`, wallpaperFormatNames(), maxWallpaperMB, strings.Join(wallpaperModes, " or ")),
+		Example: "  $ basecamp projects wallpaper set skyline.jpg --mode fill --project 12345",
+		Args:    cobra.MaximumNArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if len(args) == 0 {
+				return missingArg(cmd, "<file>")
+			}
+			if mode != "" {
+				if err := validateWallpaperMode(mode); err != nil {
+					return err
+				}
+			}
+			path, contentType, err := wallpaperFile(args[0])
+			if err != nil {
+				return err
+			}
+
+			app := appctx.FromContext(cmd.Context())
+			scope := newFollowUpScope(app)
+			projectID, err := wallpaperProjectID(cmd, app)
+			if err != nil {
+				return err
+			}
+
+			f, err := os.Open(path)
+			if err != nil {
+				return fmt.Errorf("%s: %w", args[0], err)
+			}
+			defer f.Close()
+
+			filename := filepath.Base(path)
+			opts := &basecamp.UpdateProjectWallpaperOptions{Mode: mode}
+			if err := app.Account().Projects().UpdateWallpaper(cmd.Context(), projectID, f, filename, contentType, opts); err != nil {
+				return convertSDKError(err)
+			}
+
+			summary := "Wallpaper set: " + filename
+			if mode != "" {
+				summary += " (" + mode + ")"
+			}
+			return respondWithWallpaperProject(cmd, app, projectID, scope, map[string]any{"id": projectID}, summary,
+				output.Breadcrumb{
+					Action:      "mode",
+					Cmd:         fmt.Sprintf("basecamp projects wallpaper mode <fill|tile> --project %d", projectID),
+					Description: "Change how the wallpaper is laid out",
+				},
+				output.Breadcrumb{
+					Action:      "remove",
+					Cmd:         fmt.Sprintf("basecamp projects wallpaper remove --project %d", projectID),
+					Description: "Remove the wallpaper",
+				},
+			)
+		},
+	}
+
+	cmd.Flags().StringVar(&mode, "mode", "", "Lay the image out: "+strings.Join(wallpaperModes, " or ")+" (default: keep the current mode)")
+	_ = cmd.RegisterFlagCompletionFunc("mode", cobra.FixedCompletions(wallpaperModes, cobra.ShellCompDirectiveNoFileComp))
+
+	return cmd
+}
+
+func newProjectsWallpaperModeCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:         "mode <fill|tile>",
+		Annotations: wallpaperAgentNotes(),
+		Short:       "Change how a project's wallpaper is laid out",
+		Long: `Change how the project's wallpaper is laid out. fill scales one copy to
+cover the page; tile repeats the image at its own size.
+
+A project with no wallpaper keeps the mode for the next one uploaded.`,
+		Example:   "  $ basecamp projects wallpaper mode tile --project 12345",
+		Args:      cobra.MaximumNArgs(1),
+		ValidArgs: wallpaperModes,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if len(args) == 0 {
+				return missingArg(cmd, "<fill|tile>")
+			}
+			mode := args[0]
+			if err := validateWallpaperMode(mode); err != nil {
+				return err
+			}
+
+			app := appctx.FromContext(cmd.Context())
+			scope := newFollowUpScope(app)
+			projectID, err := wallpaperProjectID(cmd, app)
+			if err != nil {
+				return err
+			}
+
+			// The SDK's update requires a name, so send the current one back.
+			current, err := app.Account().Projects().Get(cmd.Context(), projectID)
+			if err != nil {
+				return convertSDKError(err)
+			}
+			req := &basecamp.UpdateProjectRequest{Name: current.Name, WallpaperMode: mode}
+			project, err := app.Account().Projects().Update(cmd.Context(), projectID, req)
+			if err != nil {
+				return convertSDKError(err)
+			}
+
+			return respondWithWallpaperProject(cmd, app, projectID, scope, project, "Wallpaper mode set to "+mode,
+				output.Breadcrumb{
+					Action:      "set",
+					Cmd:         fmt.Sprintf("basecamp projects wallpaper set <file> --project %d", projectID),
+					Description: "Upload a wallpaper",
+				},
+			)
+		},
+	}
+}
+
+func newProjectsWallpaperRemoveCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:         "remove",
+		Annotations: wallpaperAgentNotes(),
+		Short:       "Remove a project's wallpaper",
+		Long:        "Remove the project's wallpaper. Removing it from a project that has none succeeds.",
+		Example:     "  $ basecamp projects wallpaper remove --project 12345",
+		Args:        cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			app := appctx.FromContext(cmd.Context())
+			scope := newFollowUpScope(app)
+			projectID, err := wallpaperProjectID(cmd, app)
+			if err != nil {
+				return err
+			}
+
+			if err := app.Account().Projects().RemoveWallpaper(cmd.Context(), projectID); err != nil {
+				return convertSDKError(err)
+			}
+
+			return respondWithWallpaperProject(cmd, app, projectID, scope, map[string]any{"id": projectID}, "Wallpaper removed",
+				output.Breadcrumb{
+					Action:      "set",
+					Cmd:         fmt.Sprintf("basecamp projects wallpaper set <file> --project %d", projectID),
+					Description: "Upload a new wallpaper",
+				},
+			)
+		},
+	}
+}
+
+// wallpaperFile checks the size and MIME hint before uploading. The server's
+// shared image validations remain authoritative.
+func wallpaperFile(arg string) (path, contentType string, err error) {
+	path = richtext.NormalizeDragPath(arg)
+	if err := richtext.ValidateFile(path); err != nil {
+		return "", "", fmt.Errorf("%s: %w", arg, err)
+	}
+	info, err := os.Stat(path)
+	if err != nil {
+		return "", "", fmt.Errorf("%s: %w", arg, err)
+	}
+	name := filepath.Base(path)
+	if info.Size() > maxWallpaperMB<<20 {
+		return "", "", output.ErrUsage(fmt.Sprintf("%s exceeds maximum wallpaper size of %d MB", name, maxWallpaperMB))
+	}
+	contentType = richtext.DetectMIME(path)
+	for _, f := range wallpaperFormats {
+		if f.mime == contentType {
+			return path, contentType, nil
+		}
+	}
+	return "", "", output.ErrUsage(fmt.Sprintf("%s: unsupported image type %s (use %s)", name, contentType, wallpaperFormatNames()))
+}
+
+// wallpaperFormatNames lists the accepted formats for help and validation errors.
+func wallpaperFormatNames() string {
+	names := make([]string, len(wallpaperFormats))
+	for i, f := range wallpaperFormats {
+		names[i] = f.name
+	}
+	return strings.Join(names[:len(names)-1], ", ") + ", or " + names[len(names)-1]
+}
+
+func validateWallpaperMode(mode string) error {
+	if slices.Contains(wallpaperModes, mode) {
+		return nil
+	}
+	return output.ErrUsageHint(fmt.Sprintf("unknown wallpaper mode %q", mode), "Use "+strings.Join(wallpaperModes, " or "))
+}
+
+func wallpaperProjectID(cmd *cobra.Command, app *appctx.App) (int64, error) {
+	if err := ensureAccount(cmd, app); err != nil {
+		return 0, err
+	}
+	resolved, err := resolveProjectID(cmd, app, "")
+	if err != nil {
+		return 0, err
+	}
+	projectID, err := strconv.ParseInt(resolved, 10, 64)
+	if err != nil {
+		return 0, output.ErrUsage("Invalid project ID")
+	}
+	return projectID, nil
+}
+
+// respondWithWallpaperProject answers with the project as it now stands, so
+// the output carries its wallpaper. The change has already happened, so a
+// failed read falls back to what the caller has, with a diagnostic, rather
+// than failing the command.
+func respondWithWallpaperProject(cmd *cobra.Command, app *appctx.App, projectID int64, scope followUpScope, fallback any, summary string, crumbs ...output.Breadcrumb) error {
+	crumbs = append([]output.Breadcrumb{{
+		Action:      "show",
+		Cmd:         fmt.Sprintf("basecamp projects show %d", projectID),
+		Description: "View the project",
+	}}, crumbs...)
+	scopeArgs := scope.args(app.Config.AccountID)
+	for i := range crumbs {
+		crumbs[i].Cmd += scopeArgs
+	}
+	opts := []output.ResponseOption{
+		output.WithEntity("project"),
+		output.WithSummary(summary),
+		output.WithBreadcrumbs(crumbs...),
+	}
+	data := fallback
+	project, err := app.Account().Projects().Get(cmd.Context(), projectID)
+	if err != nil {
+		opts = append(opts, output.WithDiagnostic(fmt.Sprintf("%s, but fetching the latest project state failed: %v", summary, err)))
+	} else {
+		data = project
+	}
+	return app.OK(data, opts...)
+}
+
 // convertSDKError converts SDK errors to output errors for consistent CLI error handling.
 func convertSDKError(err error) error {
 	if err == nil {
diff --git a/internal/commands/projects_wallpaper_test.go b/internal/commands/projects_wallpaper_test.go
new file mode 100644
index 000000000..761f3a71d
--- /dev/null
+++ b/internal/commands/projects_wallpaper_test.go
@@ -0,0 +1,411 @@
+package commands
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"mime"
+	"mime/multipart"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/basecamp/basecamp-cli/internal/appctx"
+	"github.com/basecamp/basecamp-cli/internal/config"
+	"github.com/basecamp/basecamp-cli/internal/output"
+)
+
+const wallpaperURL = "https://3.basecampapi.com/99999/projects/123/wallpaper?v=1"
+
+// wallpaperServer plays bc3's side of the wallpaper endpoints for project 123:
+// it records each request and keeps the wallpaper the requests leave behind,
+// so a re-read of the project shows what the change did.
+type wallpaperServer struct {
+	t        *testing.T
+	mu       sync.Mutex
+	requests []wallpaperRequest
+	attached bool
+	mode     string
+	refuse   string
+}
+
+type wallpaperRequest struct {
+	method, path, mode string
+	upload             *wallpaperUpload
+	update             map[string]any
+}
+
+type wallpaperUpload struct {
+	field, filename, contentType string
+	data                         []byte
+}
+
+func newWallpaperServer(t *testing.T) (*wallpaperServer, *appctx.App, *bytes.Buffer) {
+	t.Helper()
+	s := &wallpaperServer{t: t, mode: "fill"}
+	server := httptest.NewServer(http.HandlerFunc(s.serve))
+	t.Cleanup(server.Close)
+	app, buf := newRequestLevelApp(t, server.URL)
+	return s, app, buf
+}
+
+func (s *wallpaperServer) serve(w http.ResponseWriter, r *http.Request) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	req := wallpaperRequest{method: r.Method, path: r.URL.Path, mode: r.URL.Query().Get("mode")}
+	w.Header().Set("Content-Type", "application/json")
+
+	switch {
+	case r.Method == http.MethodPut && r.URL.Path == "/99999/projects/123/wallpaper.json":
+		req.upload = s.readUpload(r)
+		s.requests = append(s.requests, req)
+		if s.refuse != "" {
+			w.WriteHeader(http.StatusUnprocessableEntity)
+			fmt.Fprintf(w, `{"error":%q}`, s.refuse)
+			return
+		}
+		s.attached = true
+		if req.mode != "" {
+			s.mode = req.mode
+		}
+		w.WriteHeader(http.StatusNoContent)
+	case r.Method == http.MethodDelete && r.URL.Path == "/99999/projects/123/wallpaper.json":
+		s.requests = append(s.requests, req)
+		s.attached = false
+		w.WriteHeader(http.StatusNoContent)
+	case r.Method == http.MethodPut && r.URL.Path == "/99999/projects/123":
+		require.NoError(s.t, json.NewDecoder(r.Body).Decode(&req.update))
+		s.requests = append(s.requests, req)
+		if mode, ok := req.update["wallpaper_mode"].(string); ok {
+			s.mode = mode
+		}
+		fmt.Fprint(w, s.projectJSON())
+	case r.Method == http.MethodGet && r.URL.Path == "/99999/projects/123":
+		s.requests = append(s.requests, req)
+		fmt.Fprint(w, s.projectJSON())
+	default:
+		s.requests = append(s.requests, req)
+		w.WriteHeader(http.StatusNotFound)
+		fmt.Fprint(w, `{"error":"not found"}`)
+	}
+}
+
+func (s *wallpaperServer) readUpload(r *http.Request) *wallpaperUpload {
+	_, params, err := mime.ParseMediaType(r.Header.Get("Content-Type"))
+	require.NoError(s.t, err)
+	part, err := multipart.NewReader(r.Body, params["boundary"]).NextPart()
+	require.NoError(s.t, err)
+	data, err := io.ReadAll(part)
+	require.NoError(s.t, err)
+	return &wallpaperUpload{
+		field:       part.FormName(),
+		filename:    part.FileName(),
+		contentType: part.Header.Get("Content-Type"),
+		data:        data,
+	}
+}
+
+func (s *wallpaperServer) projectJSON() string {
+	if !s.attached {
+		return `{"id":123,"name":"Launch","description":"Keep me"}`
+	}
+	return fmt.Sprintf(`{"id":123,"name":"Launch","description":"Keep me","wallpaper":{"url":%q,"mode":%q}}`, wallpaperURL, s.mode)
+}
+
+func (s *wallpaperServer) calls() []string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	out := make([]string, len(s.requests))
+	for i, r := range s.requests {
+		out[i] = r.method + " " + r.path
+	}
+	return out
+}
+
+func (s *wallpaperServer) request(method, path string) wallpaperRequest {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for _, r := range s.requests {
+		if r.method == method && r.path == path {
+			return r
+		}
+	}
+	s.t.Fatalf("no %s %s among %v", method, path, s.requests)
+	return wallpaperRequest{}
+}
+
+type wallpaperEnvelope struct {
+	OK          bool                `json:"ok"`
+	Summary     string              `json:"summary"`
+	Notice      string              `json:"notice"`
+	Breadcrumbs []output.Breadcrumb `json:"breadcrumbs"`
+	Data        map[string]any      `json:"data"`
+}
+
+func decodeWallpaperEnvelope(t *testing.T, buf *bytes.Buffer) wallpaperEnvelope {
+	t.Helper()
+	var env wallpaperEnvelope
+	require.NoError(t, json.Unmarshal(buf.Bytes(), &env), "output: %s", buf.String())
+	return env
+}
+
+func writeWallpaperFile(t *testing.T, name string, size int64) string {
+	t.Helper()
+	path := filepath.Join(t.TempDir(), name)
+	require.NoError(t, os.WriteFile(path, []byte("\x89PNG\r\n\x1a\n"), 0o600))
+	if size > 0 {
+		require.NoError(t, os.Truncate(path, size))
+	}
+	return path
+}
+
+func TestProjectsWallpaperSetUploadsTheFileAndReturnsTheProject(t *testing.T) {
+	s, app, buf := newWallpaperServer(t)
+	app.Flags.Project = "123"
+	path := writeWallpaperFile(t, "skyline.png", 0)
+
+	require.NoError(t, executeCommand(NewProjectsCmd(), app, "wallpaper", "set", path, "--mode", "tile"))
+
+	assert.Equal(t, []string{
+		"PUT /99999/projects/123/wallpaper.json",
+		"GET /99999/projects/123",
+	}, s.calls())
+	put := s.request(http.MethodPut, "/99999/projects/123/wallpaper.json")
+	assert.Equal(t, "tile", put.mode)
+	require.NotNil(t, put.upload)
+	assert.Equal(t, "wallpaper", put.upload.field)
+	assert.Equal(t, "skyline.png", put.upload.filename)
+	assert.Equal(t, "image/png", put.upload.contentType)
+	assert.Equal(t, []byte("\x89PNG\r\n\x1a\n"), put.upload.data)
+
+	env := decodeWallpaperEnvelope(t, buf)
+	assert.True(t, env.OK)
+	assert.Equal(t, "Wallpaper set: skyline.png (tile)", env.Summary)
+	assert.Equal(t, map[string]any{"url": wallpaperURL, "mode": "tile"}, env.Data["wallpaper"])
+	assert.Equal(t, "basecamp projects show 123", env.Breadcrumbs[0].Cmd)
+}
+
+func TestProjectsWallpaperFollowUpsPreserveScope(t *testing.T) {
+	for _, scope := range []struct {
+		name, profile, accountSource, suffix string
+	}{
+		{"configured account", "", string(config.SourceGlobal), ""},
+		{"active profile", "staging", "profile", " --profile staging"},
+		{"explicit account override", "staging", string(config.SourceFlag), " --profile staging --account 99999"},
+		{"selected account", "", string(config.SourcePrompt), " --account 99999"},
+	} {
+		for _, action := range []string{"set", "mode", "remove"} {
+			t.Run(scope.name+"/"+action, func(t *testing.T) {
+				_, app, buf := newWallpaperServer(t)
+				app.Flags.Project = "123"
+				app.Config.ActiveProfile = scope.profile
+				app.Config.Sources = map[string]string{"account_id": scope.accountSource}
+				args := []string{"wallpaper", action}
+				want := map[string]string{"show": "basecamp projects show 123" + scope.suffix}
+				switch action {
+				case "set":
+					args = append(args, writeWallpaperFile(t, "image.png", 0))
+					want["mode"] = "basecamp projects wallpaper mode <fill|tile> --project 123" + scope.suffix
+					want["remove"] = "basecamp projects wallpaper remove --project 123" + scope.suffix
+				case "mode":
+					args = append(args, "tile")
+					fallthrough
+				case "remove":
+					want["set"] = "basecamp projects wallpaper set <file> --project 123" + scope.suffix
+				}
+
+				require.NoError(t, executeCommand(NewProjectsCmd(), app, args...))
+				env := decodeWallpaperEnvelope(t, buf)
+				require.Len(t, env.Breadcrumbs, len(want))
+				got := make(map[string]string, len(env.Breadcrumbs))
+				for _, breadcrumb := range env.Breadcrumbs {
+					got[breadcrumb.Action] = breadcrumb.Cmd
+				}
+				assert.Equal(t, want, got)
+			})
+		}
+	}
+}
+
+func TestProjectsWallpaperSetWithoutModeKeepsTheCurrentMode(t *testing.T) {
+	s, app, buf := newWallpaperServer(t)
+	app.Config.ProjectID = "123"
+	path := writeWallpaperFile(t, "skyline.png", 0)
+
+	require.NoError(t, executeCommand(NewProjectsCmd(), app, "wallpaper", "set", path))
+
+	put := s.request(http.MethodPut, "/99999/projects/123/wallpaper.json")
+	assert.Empty(t, put.mode, "no mode is sent, so the server keeps its own")
+	env := decodeWallpaperEnvelope(t, buf)
+	assert.Equal(t, "Wallpaper set: skyline.png", env.Summary)
+	assert.Equal(t, map[string]any{"url": wallpaperURL, "mode": "fill"}, env.Data["wallpaper"])
+}
+
+func TestProjectsWallpaperSetAcceptsExactlyTheSizeCap(t *testing.T) {
+	s, app, _ := newWallpaperServer(t)
+	app.Flags.Project = "123"
+	path := writeWallpaperFile(t, "big.jpg", maxWallpaperMB<<20)
+
+	require.NoError(t, executeCommand(NewProjectsCmd(), app, "wallpaper", "set", path))
+
+	assert.Equal(t, "image/jpeg", s.request(http.MethodPut, "/99999/projects/123/wallpaper.json").upload.contentType)
+}
+
+func TestProjectsWallpaperSetAcceptsServerImageFormats(t *testing.T) {
+	for _, tc := range []struct{ filename, contentType string }{
+		{"image.png", "image/png"},
+		{"image.jpg", "image/jpeg"},
+		{"image.gif", "image/gif"},
+		{"image.webp", "image/webp"},
+		{"image.avif", "image/avif"},
+		{"image.heif", "image/heif"},
+		{"image.HEIC", "image/heic"},
+	} {
+		t.Run(tc.filename, func(t *testing.T) {
+			s, app, _ := newWallpaperServer(t)
+			app.Flags.Project = "123"
+			path := writeWallpaperFile(t, tc.filename, 0)
+
+			require.NoError(t, executeCommand(NewProjectsCmd(), app, "wallpaper", "set", path))
+			assert.Equal(t, tc.contentType, s.request(http.MethodPut, "/99999/projects/123/wallpaper.json").upload.contentType)
+		})
+	}
+}
+
+func TestProjectsWallpaperSetRefusesBeforeAnyRequest(t *testing.T) {
+	cases := []struct {
+		name, file string
+		size       int64
+		args       []string
+		message    string
+	}{
+		{"over the size cap", "big.png", maxWallpaperMB<<20 + 1, nil, "big.png exceeds maximum wallpaper size of 10 MB"},
+		{"an SVG", "image.svg", 0, nil, "image.svg: unsupported image type image/svg+xml (use PNG, JPEG, GIF, WebP, AVIF, HEIF, or HEIC)"},
+		{"plain text", "notes.txt", 0, nil, "notes.txt: unsupported image type text/plain (use PNG, JPEG, GIF, WebP, AVIF, HEIF, or HEIC)"},
+		{"an unknown mode", "skyline.png", 0, []string{"--mode", "stretch"}, `unknown wallpaper mode "stretch"`},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			s, app, _ := newWallpaperServer(t)
+			app.Flags.Project = "123"
+			path := writeWallpaperFile(t, tc.file, tc.size)
+
+			err := executeCommand(NewProjectsCmd(), app, append([]string{"wallpaper", "set", path}, tc.args...)...)
+
+			var outErr *output.Error
+			require.ErrorAs(t, err, &outErr)
+			assert.Equal(t, output.CodeUsage, outErr.Code)
+			assert.Equal(t, tc.message, outErr.Message)
+			assert.Empty(t, s.calls())
+		})
+	}
+}
+
+func TestProjectsWallpaperSetRefusesAMissingFileBeforeAnyRequest(t *testing.T) {
+	s, app, _ := newWallpaperServer(t)
+	app.Flags.Project = "123"
+
+	err := executeCommand(NewProjectsCmd(), app, "wallpaper", "set", filepath.Join(t.TempDir(), "nope.png"))
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "nope.png")
+	assert.Empty(t, s.calls())
+}
+
+func TestProjectsWallpaperSetCarriesTheServersRefusal(t *testing.T) {
+	s, app, _ := newWallpaperServer(t)
+	s.refuse = "Wallpaper is not an allowed image type"
+	app.Flags.Project = "123"
+	path := writeWallpaperFile(t, "disguised.png", 0)
+
+	err := executeCommand(NewProjectsCmd(), app, "wallpaper", "set", path)
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), s.refuse)
+	assert.Equal(t, []string{"PUT /99999/projects/123/wallpaper.json"}, s.calls(), "a refused upload is not followed by a read")
+}
+
+func TestProjectsWallpaperModeSendsTheCurrentNameWithTheMode(t *testing.T) {
+	s, app, buf := newWallpaperServer(t)
+	s.attached = true
+	app.Flags.Project = "123"
+
+	require.NoError(t, executeCommand(NewProjectsCmd(), app, "wallpaper", "mode", "tile"))
+
+	assert.Equal(t, []string{
+		"GET /99999/projects/123",
+		"PUT /99999/projects/123",
+		"GET /99999/projects/123",
+	}, s.calls())
+	assert.Equal(t, map[string]any{"name": "Launch", "wallpaper_mode": "tile"},
+		s.request(http.MethodPut, "/99999/projects/123").update,
+		"only the name rides along, so the description is left alone")
+
+	env := decodeWallpaperEnvelope(t, buf)
+	assert.Equal(t, "Wallpaper mode set to tile", env.Summary)
+	assert.Equal(t, map[string]any{"url": wallpaperURL, "mode": "tile"}, env.Data["wallpaper"])
+}
+
+func TestProjectsWallpaperModeRefusesAnUnknownModeBeforeAnyRequest(t *testing.T) {
+	s, app, _ := newWallpaperServer(t)
+	app.Flags.Project = "123"
+
+	err := executeCommand(NewProjectsCmd(), app, "wallpaper", "mode", "Tile")
+
+	var outErr *output.Error
+	require.ErrorAs(t, err, &outErr)
+	assert.Equal(t, output.CodeUsage, outErr.Code)
+	assert.Equal(t, `unknown wallpaper mode "Tile"`, outErr.Message)
+	assert.Equal(t, "Use fill or tile", outErr.Hint)
+	assert.Empty(t, s.calls())
+}
+
+func TestProjectsWallpaperRemoveDeletesAndReturnsTheProjectWithoutWallpaper(t *testing.T) {
+	s, app, buf := newWallpaperServer(t)
+	s.attached = true
+	app.Flags.Project = "123"
+
+	require.NoError(t, executeCommand(NewProjectsCmd(), app, "wallpaper", "remove"))
+
+	assert.Equal(t, []string{
+		"DELETE /99999/projects/123/wallpaper.json",
+		"GET /99999/projects/123",
+	}, s.calls())
+	env := decodeWallpaperEnvelope(t, buf)
+	assert.Equal(t, "Wallpaper removed", env.Summary)
+	assert.Equal(t, float64(123), env.Data["id"])
+	assert.NotContains(t, env.Data, "wallpaper")
+}
+
+func TestProjectsWallpaperReportsAFailedReadAfterTheChange(t *testing.T) {
+	var calls []string
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		calls = append(calls, r.Method+" "+r.URL.Path)
+		if r.Method == http.MethodDelete {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusBadRequest)
+		fmt.Fprint(w, `{"error":"boom"}`)
+	}))
+	t.Cleanup(server.Close)
+	app, buf := newRequestLevelApp(t, server.URL)
+	app.Flags.Project = "123"
+
+	require.NoError(t, executeCommand(NewProjectsCmd(), app, "wallpaper", "remove"))
+
+	assert.Equal(t, []string{"DELETE /99999/projects/123/wallpaper.json", "GET /99999/projects/123"}, calls)
+	env := decodeWallpaperEnvelope(t, buf)
+	assert.True(t, env.OK)
+	assert.Equal(t, float64(123), env.Data["id"])
+	assert.Contains(t, env.Notice, "Wallpaper removed, but fetching the latest project state failed")
+}
diff --git a/internal/mcpserver/catalog_test.go b/internal/mcpserver/catalog_test.go
index e92884a0e..d785902aa 100644
--- a/internal/mcpserver/catalog_test.go
+++ b/internal/mcpserver/catalog_test.go
@@ -55,10 +55,11 @@ func TestCatalogClaimsEveryTag(t *testing.T) {
 func TestCatalogExcludesUnservedOperations(t *testing.T) {
 	cat := loadForTest(t)
 	excluded := map[string]bool{
-		"CreateAttachment":     true,
-		"CreateCampfireUpload": true,
-		"UpdateAccountLogo":    true,
-		"CreateStreamTicket":   true,
+		"CreateAttachment":       true,
+		"CreateCampfireUpload":   true,
+		"UpdateAccountLogo":      true,
+		"UpdateProjectWallpaper": true,
+		"CreateStreamTicket":     true,
 	}
 	model, composite := 0, 0
 	for _, d := range cat.Domains {
@@ -71,7 +72,7 @@ func TestCatalogExcludesUnservedOperations(t *testing.T) {
 			assert.False(t, excluded[op.ID], "operation %q should be excluded from the vendored model", op.ID)
 		}
 	}
-	assert.Equal(t, 281, model, "served model operation count")
+	assert.Equal(t, 282, model, "served model operation count")
 	assert.Equal(t, 1, composite, "served composite operation count")
 }
 
diff --git a/internal/mcpserver/model/PROVENANCE.json b/internal/mcpserver/model/PROVENANCE.json
index 42ac0b999..d0588379b 100644
--- a/internal/mcpserver/model/PROVENANCE.json
+++ b/internal/mcpserver/model/PROVENANCE.json
@@ -1,7 +1,7 @@
 {
   "source": "github.com/basecamp/basecamp-sdk",
-  "commit": "63115e7978c989a271220cee8b025135315db882",
-  "ref": "v0.27.1-3-g63115e79",
+  "commit": "1850988c288405541bc785e4a9f9e06fce7ff458",
+  "ref": "v0.28.0",
   "files": ["behavior-model.json", "openapi.json"],
   "synced_by": "scripts/sync-mcp-model.sh",
   "patches": "binary-upload operations dropped because the toolkit refuses their non-JSON bodies (EXCLUDED_OPERATIONS) and the stream-ticket mint dropped by policy (POLICY_EXCLUDED_OPERATIONS); no tag patches applied (PATCHED_TAGS is empty — the export tags every operation) — see the sync script"
diff --git a/internal/mcpserver/model/behavior-model.json b/internal/mcpserver/model/behavior-model.json
index a8bc4d3b9..9d8057658 100644
--- a/internal/mcpserver/model/behavior-model.json
+++ b/internal/mcpserver/model/behavior-model.json
@@ -2789,6 +2789,18 @@
         ]
       }
     },
+    "RemoveProjectWallpaper": {
+      "idempotent": true,
+      "retry": {
+        "max": 3,
+        "base_delay_ms": 1000,
+        "backoff": "exponential",
+        "retry_on": [
+          429,
+          503
+        ]
+      }
+    },
     "ReorderUpNext": {
       "retry": {
         "max": 3,
diff --git a/internal/mcpserver/model/openapi.json b/internal/mcpserver/model/openapi.json
index d95723c84..8cf097de9 100644
--- a/internal/mcpserver/model/openapi.json
+++ b/internal/mcpserver/model/openapi.json
@@ -16481,6 +16481,104 @@
         }
       }
     },
+    "/{accountId}/projects/{projectId}/wallpaper.json": {
+      "delete": {
+        "description": "Remove the project's wallpaper (returns 204 No Content).\nPeople and personal assistants follow project-edit permissions; shared agents are refused.",
+        "operationId": "RemoveProjectWallpaper",
+        "parameters": [
+          {
+            "name": "accountId",
+            "in": "path",
+            "description": "Basecamp account ID (numeric string)",
+            "schema": {
+              "type": "string",
+              "pattern": "^[0-9]+$",
+              "description": "Basecamp account ID (numeric string)"
+            },
+            "required": true
+          },
+          {
+            "name": "projectId",
+            "in": "path",
+            "schema": {
+              "type": "integer",
+              "format": "int64"
+            },
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "description": "RemoveProjectWallpaper 204 response"
+          },
+          "401": {
+            "description": "UnauthorizedError 401 response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/UnauthorizedErrorResponseContent"
+                }
+              }
+            }
+          },
+          "403": {
+            "description": "ForbiddenError 403 response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ForbiddenErrorResponseContent"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "NotFoundError 404 response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/NotFoundErrorResponseContent"
+                }
+              }
+            }
+          },
+          "429": {
+            "description": "RateLimitError 429 response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/RateLimitErrorResponseContent"
+                }
+              }
+            }
+          },
+          "500": {
+            "description": "InternalServerError 500 response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/InternalServerErrorResponseContent"
+                }
+              }
+            }
+          }
+        },
+        "tags": [
+          "Projects"
+        ],
+        "x-basecamp-idempotent": {
+          "natural": true
+        },
+        "x-basecamp-retry": {
+          "maxAttempts": 3,
+          "baseDelayMs": 1000,
+          "backoff": "exponential",
+          "retryOn": [
+            429,
+            503
+          ]
+        }
+      }
+    },
     "/{accountId}/question_answers/{answerId}": {
       "get": {
         "description": "Get a single answer by id",
@@ -36532,6 +36630,9 @@
           "client_company": {
             "$ref": "#/components/schemas/ClientCompany"
           },
+          "wallpaper": {
+            "$ref": "#/components/schemas/ProjectWallpaper"
+          },
           "clientside": {
             "$ref": "#/components/schemas/ClientSide",
             "deprecated": true,
@@ -36634,6 +36735,24 @@
           "error"
         ]
       },
+      "ProjectWallpaper": {
+        "type": "object",
+        "description": "The project's wallpaper, included only in single-project responses when attached.\nProject lists and home responses omit it.",
+        "properties": {
+          "url": {
+            "type": "string",
+            "description": "An authenticated API-host URL that redirects to the wallpaper image in storage, not a public image link.\nUse the SDK's authenticated download helper instead of placing this URL directly in an image element."
+          },
+          "mode": {
+            "type": "string",
+            "description": "fill|tile"
+          }
+        },
+        "required": [
+          "mode",
+          "url"
+        ]
+      },
       "Question": {
         "type": "object",
         "properties": {
@@ -40304,6 +40423,10 @@
           },
           "schedule_attributes": {
             "$ref": "#/components/schemas/ScheduleAttributes"
+          },
+          "wallpaper_mode": {
+            "type": "string",
+            "description": "How the project's wallpaper is laid out. Changes only the layout of a\nwallpaper already attached; UpdateProjectWallpaper uploads one."
           }
         },
         "required": [
@@ -40313,6 +40436,10 @@
       "UpdateProjectResponseContent": {
         "$ref": "#/components/schemas/Project"
       },
+      "UpdateProjectWallpaperInputPayload": {
+        "type": "string",
+        "contentEncoding": "byte"
+      },
       "UpdateQuestionNotificationSettingsRequestContent": {
         "type": "object",
         "properties": {
diff --git a/internal/mcpserver/testdata/catalog_snapshot.txt b/internal/mcpserver/testdata/catalog_snapshot.txt
index f2a6e0635..e71d07449 100644
--- a/internal/mcpserver/testdata/catalog_snapshot.txt
+++ b/internal/mcpserver/testdata/catalog_snapshot.txt
@@ -11,6 +11,7 @@ ACTIONS (RO = read-only):
 - list_projects (RO, paginated): List projects (active by default; optionally archived/trashed)
 - list_recent_projects (RO): List the projects the current user has most recently visited, most recent visit first
 - record_project_visit: Record that the current user visited a project, moving it to the front of ListRecentProjects (returns 204 No Content)
+- remove_project_wallpaper: Remove the project's wallpaper (returns 204 No Content)
 - trash_project: Trash a project (returns 204 No Content)
 - unarchive_project: Restore a project to active status from trash as well as from the archive (returns 204 No Content)
 - update_project: Update an existing project
diff --git a/internal/presenter/format.go b/internal/presenter/format.go
index 80b58c9d6..c99668dc3 100644
--- a/internal/presenter/format.go
+++ b/internal/presenter/format.go
@@ -30,11 +30,24 @@ func FormatField(spec FieldSpec, key string, val any, locale Locale) string {
 		return formatDock(val)
 	case "steps":
 		return formatSteps(val)
+	case "wallpaper":
+		return formatWallpaper(val)
 	default:
 		return formatText(val)
 	}
 }
 
+// formatWallpaper names how a project's wallpaper is laid out. Its URL is a
+// signed-in redirect, no use to read in a terminal.
+func formatWallpaper(val any) string {
+	if m, ok := val.(map[string]any); ok {
+		if mode, ok := m["mode"].(string); ok {
+			return richtext.SanitizeSingleLine(mode)
+		}
+	}
+	return ""
+}
+
 // formatSteps renders a CardStep array as a multi-line checklist.
 // Each step prefixes its title with [x] for completed, [ ] for active.
 func formatSteps(val any) string {
diff --git a/internal/presenter/presenter_test.go b/internal/presenter/presenter_test.go
index 4a02c68b2..03b87bd06 100644
--- a/internal/presenter/presenter_test.go
+++ b/internal/presenter/presenter_test.go
@@ -690,6 +690,21 @@ func TestPresentEmptySliceMarkdownTable(t *testing.T) {
 	}
 }
 
+func TestProjectDetailNamesTheWallpaperMode(t *testing.T) {
+	project := map[string]any{"id": float64(123), "name": "Launch", "status": "active"}
+
+	var without strings.Builder
+	require.True(t, PresentWithTheme(&without, project, "project", ModeMarkdown, tui.NoColorTheme(), enUS))
+	assert.NotContains(t, without.String(), "Wallpaper")
+
+	project["wallpaper"] = map[string]any{"url": "https://3.basecamp.com/1/projects/123/wallpaper", "mode": "tile"}
+	var with strings.Builder
+	require.True(t, PresentWithTheme(&with, project, "project", ModeMarkdown, tui.NoColorTheme(), enUS))
+	assert.Contains(t, with.String(), "Wallpaper")
+	assert.Contains(t, with.String(), "tile")
+	assert.NotContains(t, with.String(), "/wallpaper")
+}
+
 // =============================================================================
 // Collapse Tests
 // =============================================================================
diff --git a/internal/presenter/schemas/project.yaml b/internal/presenter/schemas/project.yaml
index cd0c62501..900bb1185 100644
--- a/internal/presenter/schemas/project.yaml
+++ b/internal/presenter/schemas/project.yaml
@@ -29,6 +29,10 @@ fields:
     role: detail
     format: text
 
+  wallpaper:
+    role: detail
+    format: wallpaper
+
   dock:
     role: body
     format: dock
@@ -52,7 +56,7 @@ views:
     sections:
       - fields: [name, description]
       - heading: Info
-        fields: [status, bookmarked]
+        fields: [status, bookmarked, wallpaper]
       - heading: Dock
         fields: [dock]
       - heading: Metadata
diff --git a/internal/richtext/mime.go b/internal/richtext/mime.go
index 22dad5cfb..a1ea5385a 100644
--- a/internal/richtext/mime.go
+++ b/internal/richtext/mime.go
@@ -31,6 +31,7 @@ var mimeByExt = map[string]string{
 	".webp": "image/webp",
 	".avif": "image/avif",
 	".heic": "image/heic",
+	".heif": "image/heif",
 	".svg":  "image/svg+xml",
 	".ico":  "image/x-icon",
 	".mp4":  "video/mp4",
diff --git a/internal/richtext/mime_test.go b/internal/richtext/mime_test.go
index e7c380910..458a7352f 100644
--- a/internal/richtext/mime_test.go
+++ b/internal/richtext/mime_test.go
@@ -16,6 +16,8 @@ func TestDetectMIME(t *testing.T) {
 		{"data.json", "application/json"},
 		{"README.md", "text/markdown"},
 		{"photo.jpeg", "image/jpeg"},
+		{"photo.HEIC", "image/heic"},
+		{"photo.heif", "image/heif"},
 		{"archive.zip", "application/zip"},
 		{"style.css", "application/octet-stream"}, // not in our map, file doesn't exist
 		{"doc.docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document"},
diff --git a/internal/version/sdk-provenance.json b/internal/version/sdk-provenance.json
index f0239d2a0..b7129ec5e 100644
--- a/internal/version/sdk-provenance.json
+++ b/internal/version/sdk-provenance.json
@@ -1,9 +1,9 @@
 {
   "sdk": {
     "module": "github.com/basecamp/basecamp-sdk/go",
-    "version": "v0.27.1-0.20261022230746-63115e7978c9",
-    "revision": "63115e7978c9",
-    "updated_at": "2026-10-22T23:07:46Z"
+    "version": "v0.28.0",
+    "revision": "1850988c2884",
+    "updated_at": "2026-10-23T23:22:11Z"
   },
   "api": {
     "repo": "basecamp/bc3",
diff --git a/nix/package.nix b/nix/package.nix
index 650dca96b..25120130f 100644
--- a/nix/package.nix
+++ b/nix/package.nix
@@ -8,7 +8,7 @@ buildGoModule.override { go = go_1_26; } (finalAttrs: {
   src = lib.cleanSource ./..;
 
   # To update: set to lib.fakeHash, run `nix build`, use the hash from the error.
-  vendorHash = "sha256-TqjNLGbA3/mruCH8TA4HaGHYLnsXLK66fUuXp4ye9eQ=";
+  vendorHash = "sha256-JNG5aUCyIcuhsmdCd+6DocMeUff5geyEbPVqy+GlQio=";
 
   subPackages = [ "cmd/basecamp" ];
 
diff --git a/scripts/sync-mcp-model.sh b/scripts/sync-mcp-model.sh
index 5912137bc..894991fbc 100755
--- a/scripts/sync-mcp-model.sh
+++ b/scripts/sync-mcp-model.sh
@@ -61,6 +61,7 @@ EXCLUDED_OPERATIONS = {
     "CreateAttachment",
     "CreateCampfireUpload",
     "UpdateAccountLogo",
+    "UpdateProjectWallpaper",
 }
 
 # Excluded by policy rather than by body shape, so these are not held to the
diff --git a/skill-evals/cases/project-wallpaper.yml b/skill-evals/cases/project-wallpaper.yml
new file mode 100644
index 000000000..b1535c3f3
--- /dev/null
+++ b/skill-evals/cases/project-wallpaper.yml
@@ -0,0 +1,9 @@
+task: Use ./skyline.png as the wallpaper for project 55555, repeated as a tile
+tags: [domain, update]
+accept:
+  - 'projects? wallpaper set .*skyline\.png'
+  - '--mode tile'
+  - '(--in|--project|-p) 55555'
+reject:
+  - 'projects? update'
+  - 'basecamp api'
diff --git a/skills/basecamp/SKILL.md b/skills/basecamp/SKILL.md
index 479bce387..3495c9ad7 100644
--- a/skills/basecamp/SKILL.md
+++ b/skills/basecamp/SKILL.md
@@ -10,6 +10,7 @@ triggers:
   - basecamp todos
   - basecamp subtasks
   - basecamp project
+  - project wallpaper
   - basecamp cards
   - basecamp chat
   - basecamp campfire
@@ -231,6 +232,28 @@ basecamp spotlight <id|url> --agent
 basecamp unspotlight <id|url> --agent
 ```
 
+## Project wallpaper
+
+The wallpaper is the image behind a project's pages. The `projects wallpaper`
+group sets, lays out, and removes it, for the project in `--in`/`--project` or
+the configured default:
+
+```bash
+basecamp projects wallpaper set skyline.jpg --mode tile --in "<project>" --json
+basecamp projects wallpaper mode fill --in "<project>" --json
+basecamp projects wallpaper remove --in "<project>" --json
+```
+
+- People and personal assistants follow project-edit permissions. Shared
+  agents are refused (403); do not retry or route around that refusal.
+- The CLI checks the file's size and MIME hint before uploading; leaf help
+  names the limits. Server image validations still apply. `--mode` is `fill`
+  or `tile`, and leaving it out keeps the current mode.
+- Each command returns the project. `.data.wallpaper` is `{url, mode}`, and is
+  absent when the project has none; `projects show` carries the same field.
+  The URL requires authentication and redirects to the image; it is not a
+  public image link.
+
 ## Content and stdin
 
 Command help declares content arguments and stdin support. Titles are generally