diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6feec6f..5798ffa 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,6 +1,12 @@
 name: Build, Test, and Deploy Dashboard
 
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
 
 permissions:
   contents: read
@@ -106,7 +112,6 @@ jobs:
           path: image-artifacts
 
       - name: Restore previously published site
-        if: ${{ github.event_name == 'push' }}
         run: |
           set -euo pipefail
           rm -rf dashboard
@@ -132,12 +137,16 @@ jobs:
       - name: Generate dashboard
         env:
           GH_TOKEN: ${{ github.token }}
+          GITHUB_HEAD_REF: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
+          GITHUB_PR_NUMBER: ${{ github.event_name == 'pull_request' && github.event.pull_request.number || '' }}
+          GITHUB_PR_TITLE: ${{ github.event_name == 'pull_request' && github.event.pull_request.title || '' }}
+          GITHUB_PR_DRAFT: ${{ github.event_name == 'pull_request' && github.event.pull_request.draft || '' }}
         run: |
           set -euo pipefail
           fpm run testboard -- \
             --image-root image-artifacts \
             --output dashboard \
-            --branch "${{ github.ref_name }}" \
+            --branch "${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.ref_name }}" \
             --commit "${{ github.sha }}" \
             --run-id "${{ github.run_id }}" \
             --repo "${{ github.repository }}" \
@@ -148,14 +157,12 @@ jobs:
         uses: actions/configure-pages@v5
 
       - name: Upload dashboard artifact
-        if: ${{ github.event_name == 'push' }}
         uses: actions/upload-pages-artifact@v3
         with:
           path: './dashboard'
 
   deploy:
     name: Deploy to GitHub Pages
-    if: github.event_name == 'push'
     needs: dashboard
     runs-on: ubuntu-latest
     permissions:
diff --git a/src/gh_api.f90 b/src/gh_api.f90
index 5e98ccc..8ec8ce0 100644
--- a/src/gh_api.f90
+++ b/src/gh_api.f90
@@ -1,166 +1,326 @@
 module gh_api
   !! GitHub API interactions via gh CLI
-  use string_utils, only: trim_null
-  use json_utils, only: branch_metadata
-  implicit none
-  private
+   use string_utils, only: starts_with, str
+   use json_utils, only: branch_metadata
+   implicit none
+   private
 
-  public :: get_pr_info, get_pr_state
+   public :: get_pr_info, get_pr_state
 
 contains
 
-  subroutine get_pr_info(branch, repo, metadata, success)
+   subroutine get_pr_info(branch, repo, metadata, success)
     !! Fetch PR information for a branch using gh CLI
-    character(len=*), intent(in) :: branch, repo
-    type(branch_metadata), intent(inout) :: metadata
-    logical, intent(out) :: success
-    character(len=1024) :: cmd, temp_file, line
-    integer :: unit, stat, ios
-    character(len=512) :: gh_token
+      character(len=*), intent(in) :: branch, repo
+      type(branch_metadata), intent(inout) :: metadata
+      logical, intent(out) :: success
+      character(len=1024) :: command
+      character(len=512) :: gh_token
+      character(len=256) :: branch_query, normalized_branch, github_ref
+      character(len=256) :: head_ref, pr_number_env, pr_title_env, pr_draft_env
+      integer :: stat, pr_number, env_pr_number, ios
+      logical :: has_token, link_parsed, command_ok, got_env_number
+
+      success = .false.
+      normalized_branch = trim(branch)
+      branch_query = normalized_branch
+
+      call get_environment_variable('GITHUB_HEAD_REF', head_ref, status=stat)
+      if (stat == 0 .and. len_trim(head_ref) > 0) then
+         branch_query = trim(head_ref)
+      end if
 
-    success = .false.
+      pr_number = parse_pr_number_from_ref(normalized_branch)
 
-    ! Check if GH_TOKEN is set
-    call get_environment_variable('GH_TOKEN', gh_token, status=stat)
-    if (stat /= 0 .or. len_trim(gh_token) == 0) then
-      return
-    end if
+      if (pr_number <= 0) then
+         call get_environment_variable('GITHUB_REF', github_ref, status=stat)
+         if (stat == 0 .and. len_trim(github_ref) > 0) then
+            pr_number = parse_pr_number_from_ref(github_ref)
+         end if
+      end if
 
-    ! Create temp file for output
-    temp_file = '/tmp/testboard_pr.json'
+      got_env_number = .false.
+      if (pr_number <= 0) then
+         call get_environment_variable('GITHUB_PR_NUMBER', pr_number_env, status=stat)
+         if (stat == 0 .and. len_trim(pr_number_env) > 0) then
+            pr_number_env = adjustl(trim(pr_number_env))
+            read (pr_number_env, *, iostat=ios) env_pr_number
+            if (ios == 0) then
+               pr_number = env_pr_number
+               got_env_number = .true.
+            end if
+         end if
+      end if
 
-    ! Call gh CLI
-    write(cmd, '(A)') 'gh pr list --repo "' // trim(repo) // '" --head "' // &
-                      trim(branch) // '" --json number,url,title,isDraft --jq ".[0]" > "' // &
-                      trim(temp_file) // '" 2>/dev/null'
+      if (pr_number > 0) then
+         if (metadata%pr_number <= 0) metadata%pr_number = pr_number
+         if (len_trim(repo) > 0) then
+            metadata%pr_url = 'https://github.com/'//trim(repo)//'/pull/'// &
+                              trim(str(pr_number))
+         end if
+      end if
 
-    call execute_command_line(trim(cmd), exitstat=stat)
+      call get_environment_variable('GITHUB_PR_TITLE', pr_title_env, status=stat)
+      if (stat == 0 .and. len_trim(pr_title_env) > 0) then
+         metadata%pr_title = trim(pr_title_env)
+      end if
 
-    if (stat /= 0) return
+      call get_environment_variable('GITHUB_PR_DRAFT', pr_draft_env, status=stat)
+      if (stat == 0 .and. len_trim(pr_draft_env) > 0) then
+         pr_draft_env = adjustl(trim(pr_draft_env))
+         read (pr_draft_env, *, iostat=ios) metadata%pr_draft
+         if (ios /= 0) metadata%pr_draft = .false.
+      end if
 
-    ! Read JSON output (simple parsing)
-    open(newunit=unit, file=temp_file, status='old', action='read', iostat=ios)
-    if (ios /= 0) return
+      link_parsed = (metadata%pr_number > 0 .and. len_trim(metadata%pr_url) > 0)
 
-    success = parse_pr_json(unit, metadata)
-    close(unit)
+      call get_environment_variable('GH_TOKEN', gh_token, status=stat)
+      has_token = (stat == 0 .and. len_trim(gh_token) > 0)
 
-    ! Clean up
-    open(newunit=unit, file=temp_file, status='old')
-    close(unit, status='delete')
-  end subroutine get_pr_info
+      if (.not. has_token) then
+         success = link_parsed
+         return
+      end if
 
-  function parse_pr_json(unit, metadata) result(success)
-    !! Parse JSON from gh pr list (simple parser for specific fields)
-    integer, intent(in) :: unit
-    type(branch_metadata), intent(inout) :: metadata
-    logical :: success
-    character(len=2048) :: line
-    integer :: ios, pos1, pos2
+      if (starts_with(branch_query, 'refs/heads/')) then
+         branch_query = trim(branch_query(len('refs/heads/') + 1:))
+      end if
 
-    success = .false.
+      if (pr_number > 0 .and. .not. got_env_number) then
+         write (command, '(A,I0,A)') 'gh pr view ', pr_number, ' --repo "'// &
+            trim(repo)//'" --json number,url,title,isDraft'
+         command_ok = run_pr_command(trim(command), metadata)
+      else
+         write (command, '(A)') 'gh pr list --repo "'//trim(repo)// &
+            '" --head "'//trim(branch_query)// &
+            '" --json number,url,title,isDraft --jq ".[0]"'
+         command_ok = run_pr_command(trim(command), metadata)
+
+         if (.not. command_ok) then
+            pr_number = parse_pr_number_from_ref(branch_query)
+            if (pr_number > 0) then
+               write (command, '(A,I0,A)') 'gh pr view ', pr_number, ' --repo "'// &
+                  trim(repo)//'" --json number,url,title,isDraft'
+               command_ok = run_pr_command(trim(command), metadata)
+            end if
+         end if
+      end if
 
-    do
-      read(unit, '(A)', iostat=ios) line
-      if (ios /= 0) exit
+      if (command_ok) then
+         success = .true.
+         if (metadata%pr_number == 0 .and. pr_number > 0) then
+            metadata%pr_number = pr_number
+         end if
+         if (len_trim(metadata%pr_url) == 0 .and. pr_number > 0 .and. &
+             len_trim(repo) > 0) then
+            metadata%pr_url = 'https://github.com/'//trim(repo)//'/pull/'// &
+                              trim(str(pr_number))
+         end if
+      else
+         success = link_parsed
+      end if
+   end subroutine get_pr_info
 
-      ! Parse "number": 123
-      if (index(line, '"number":') > 0) then
-        pos1 = index(line, ':') + 1
-        read(line(pos1:), *, iostat=ios) metadata%pr_number
-        if (ios == 0) success = .true.
+   function parse_pr_json(unit, metadata) result(success)
+    !! Parse JSON from gh pr list (simple parser for specific fields)
+      integer, intent(in) :: unit
+      type(branch_metadata), intent(inout) :: metadata
+      logical :: success
+      character(len=2048) :: line
+      integer :: ios, pos1, pos2
+
+      success = .false.
+
+      do
+         read (unit, '(A)', iostat=ios) line
+         if (ios /= 0) exit
+
+         ! Parse "number": 123
+         if (index(line, '"number":') > 0) then
+            pos1 = index(line, ':') + 1
+            read (line(pos1:), *, iostat=ios) metadata%pr_number
+            if (ios == 0) success = .true.
+         end if
+
+         ! Parse "url": "..."
+         if (index(line, '"url":') > 0) then
+            pos1 = index(line, '"', back=.true.) ! last quote
+            pos2 = index(line(:pos1 - 1), '"', back=.true.) ! second-to-last quote
+            if (pos2 > 0 .and. pos1 > pos2) then
+               metadata%pr_url = line(pos2 + 1:pos1 - 1)
+            end if
+         end if
+
+         ! Parse "title": "..."
+         if (index(line, '"title":') > 0) then
+            pos1 = index(line, '"', back=.true.)
+            pos2 = index(line(:pos1 - 1), '"', back=.true.)
+            if (pos2 > 0 .and. pos1 > pos2) then
+               metadata%pr_title = line(pos2 + 1:pos1 - 1)
+            end if
+         end if
+
+         ! Parse "isDraft": true/false
+         if (index(line, '"isDraft":') > 0) then
+            metadata%pr_draft = (index(line, 'true') > 0)
+         end if
+      end do
+   end function parse_pr_json
+
+   logical function run_pr_command(command, metadata) result(success)
+    !! Execute a gh command and parse PR metadata JSON output
+      character(len=*), intent(in) :: command
+      type(branch_metadata), intent(inout) :: metadata
+      character(len=1024) :: cmd, temp_file
+      integer :: unit, stat, ios
+
+      temp_file = '/tmp/testboard_pr.json'
+      write (cmd, '(A)') trim(command)//' > "'//trim(temp_file)// &
+         '" 2>/dev/null'
+
+      call execute_command_line(trim(cmd), exitstat=stat)
+      if (stat /= 0) then
+         success = .false.
+         call cleanup_temp_file(temp_file)
+         return
       end if
 
-      ! Parse "url": "..."
-      if (index(line, '"url":') > 0) then
-        pos1 = index(line, '"', back=.true.) ! last quote
-        pos2 = index(line(:pos1-1), '"', back=.true.) ! second-to-last quote
-        if (pos2 > 0 .and. pos1 > pos2) then
-          metadata%pr_url = line(pos2+1:pos1-1)
-        end if
+      open (newunit=unit, file=temp_file, status='old', action='read', iostat=ios)
+      if (ios /= 0) then
+         success = .false.
+         call cleanup_temp_file(temp_file)
+         return
       end if
 
-      ! Parse "title": "..."
-      if (index(line, '"title":') > 0) then
-        pos1 = index(line, '"', back=.true.)
-        pos2 = index(line(:pos1-1), '"', back=.true.)
-        if (pos2 > 0 .and. pos1 > pos2) then
-          metadata%pr_title = line(pos2+1:pos1-1)
-        end if
+      success = parse_pr_json(unit, metadata)
+      close (unit)
+      call cleanup_temp_file(temp_file)
+   end function run_pr_command
+
+   subroutine cleanup_temp_file(path)
+    !! Delete temporary file if it exists
+      character(len=*), intent(in) :: path
+      integer :: unit, ios
+
+      open (newunit=unit, file=path, status='old', action='read', iostat=ios)
+      if (ios == 0) then
+         close (unit, status='delete')
       end if
+   end subroutine cleanup_temp_file
+
+   integer function parse_pr_number_from_ref(branch) result(pr_number)
+    !! Extract PR number from GitHub ref like refs/pull/123/merge
+      character(len=*), intent(in) :: branch
+      character(len=256) :: trimmed_branch, digits
+      integer :: prefix_len, slash_pos, ios
 
-      ! Parse "isDraft": true/false
-      if (index(line, '"isDraft":') > 0) then
-        metadata%pr_draft = (index(line, 'true') > 0)
+      pr_number = 0
+      trimmed_branch = trim(branch)
+
+      if (starts_with(trimmed_branch, 'refs/pull/')) then
+         prefix_len = len('refs/pull/')
+      else if (starts_with(trimmed_branch, 'pull/')) then
+         prefix_len = len('pull/')
+      else
+         return
+      end if
+
+      slash_pos = index(trimmed_branch(prefix_len + 1:), '/')
+      if (slash_pos > 0) then
+         digits = trimmed_branch(prefix_len + 1:prefix_len + slash_pos - 1)
+      else
+         digits = trimmed_branch(prefix_len + 1:)
       end if
-    end do
-  end function parse_pr_json
 
-  function get_pr_state(pr_number, repo, state, success) result(is_open)
+      digits = trim(digits)
+      if (.not. is_all_digits(digits)) return
+
+      read (digits, *, iostat=ios) pr_number
+      if (ios /= 0) pr_number = 0
+   end function parse_pr_number_from_ref
+
+   logical function is_all_digits(text) result(all_digits)
+    !! Check whether the provided text is composed only of digits
+      character(len=*), intent(in) :: text
+      integer :: i, code
+
+      all_digits = (len_trim(text) > 0)
+      if (.not. all_digits) return
+
+      do i = 1, len_trim(text)
+         code = iachar(text(i:i))
+         if (code < iachar('0') .or. code > iachar('9')) then
+            all_digits = .false.
+            return
+         end if
+      end do
+   end function is_all_digits
+
+   function get_pr_state(pr_number, repo, state, success) result(is_open)
     !! Check if a PR is open using gh CLI
     !! Returns .true. if PR is open, .false. if closed/merged
-    integer, intent(in) :: pr_number
-    character(len=*), intent(in) :: repo
-    character(len=16), intent(out) :: state
-    logical, intent(out) :: success
-    logical :: is_open
-    character(len=1024) :: cmd
-    character(len=256) :: temp_file
-    character(len=512) :: gh_token
-    character(len=64) :: line
-    integer :: unit, stat, ios, pos1, pos2
-
-    success = .false.
-    is_open = .true.  ! Default to open (fail-safe)
-    state = 'unknown'
-
-    ! Check if GH_TOKEN is set
-    call get_environment_variable('GH_TOKEN', gh_token, status=stat)
-    if (stat /= 0 .or. len_trim(gh_token) == 0) then
-      return
-    end if
-
-    ! Create temp file for output
-    temp_file = '/tmp/testboard_pr_state.json'
-
-    ! Call gh CLI to get PR state
-    write(cmd, '(A,I0,A)') 'gh pr view ', pr_number, ' --repo "' // trim(repo) // &
-                           '" --json state --jq ".state" > "' // trim(temp_file) // '" 2>/dev/null'
-
-    call execute_command_line(trim(cmd), exitstat=stat)
-
-    if (stat /= 0) return
-
-    ! Read state from file
-    open(newunit=unit, file=temp_file, status='old', action='read', iostat=ios)
-    if (ios /= 0) return
-
-    read(unit, '(A)', iostat=ios) line
-    if (ios == 0) then
-      ! Remove quotes and newlines
-      line = adjustl(trim(line))
-      if (line(1:1) == '"') then
-        pos1 = 2
-        pos2 = index(line(2:), '"')
-        if (pos2 > 0) then
-          state = trim(line(pos1:pos1+pos2-2))
-        else
-          state = trim(line(2:))
-        end if
-      else
-        state = trim(line)
+      integer, intent(in) :: pr_number
+      character(len=*), intent(in) :: repo
+      character(len=16), intent(out) :: state
+      logical, intent(out) :: success
+      logical :: is_open
+      character(len=1024) :: cmd
+      character(len=256) :: temp_file
+      character(len=512) :: gh_token
+      character(len=64) :: line
+      integer :: unit, stat, ios, pos1, pos2
+
+      success = .false.
+      is_open = .true.  ! Default to open (fail-safe)
+      state = 'unknown'
+
+      ! Check if GH_TOKEN is set
+      call get_environment_variable('GH_TOKEN', gh_token, status=stat)
+      if (stat /= 0 .or. len_trim(gh_token) == 0) then
+         return
       end if
 
-      ! Check if state is OPEN
-      is_open = (trim(state) == 'OPEN')
-      success = .true.
-    end if
+      ! Create temp file for output
+      temp_file = '/tmp/testboard_pr_state.json'
+
+      ! Call gh CLI to get PR state
+      write (cmd, '(A,I0,A)') 'gh pr view ', pr_number, ' --repo "'//trim(repo)// &
+         '" --json state --jq ".state" > "'//trim(temp_file)//'" 2>/dev/null'
+
+      call execute_command_line(trim(cmd), exitstat=stat)
+
+      if (stat /= 0) return
+
+      ! Read state from file
+      open (newunit=unit, file=temp_file, status='old', action='read', iostat=ios)
+      if (ios /= 0) return
+
+      read (unit, '(A)', iostat=ios) line
+      if (ios == 0) then
+         ! Remove quotes and newlines
+         line = adjustl(trim(line))
+         if (line(1:1) == '"') then
+            pos1 = 2
+            pos2 = index(line(2:), '"')
+            if (pos2 > 0) then
+               state = trim(line(pos1:pos1 + pos2 - 2))
+            else
+               state = trim(line(2:))
+            end if
+         else
+            state = trim(line)
+         end if
+
+         ! Check if state is OPEN
+         is_open = (trim(state) == 'OPEN')
+         success = .true.
+      end if
 
-    close(unit)
+      close (unit)
 
-    ! Clean up
-    open(newunit=unit, file=temp_file, status='old')
-    close(unit, status='delete')
-  end function get_pr_state
+      ! Clean up
+      open (newunit=unit, file=temp_file, status='old')
+      close (unit, status='delete')
+   end function get_pr_state
 
 end module gh_api
diff --git a/src/json_utils.f90 b/src/json_utils.f90
index 6dadb1f..f5eb7e4 100644
--- a/src/json_utils.f90
+++ b/src/json_utils.f90
@@ -1,115 +1,335 @@
 module json_utils
   !! Simple JSON reading/writing for metadata
   !! This is a minimal implementation for our specific use case
-    use string_utils, only: str
-    implicit none
-    private
-
-    public :: json_write_metadata, json_read_metadata, branch_metadata
-
-    type :: branch_metadata
-        character(len=256) :: branch_name = ''
-        character(len=256) :: commit = ''
-        character(len=256) :: timestamp = ''
-        character(len=64) :: run_id = ''
-        character(len=256) :: repo = ''
-        logical :: has_pngs = .false.
-        integer :: diff_count = 0
-        integer :: pr_number = 0
-        character(len=512) :: pr_url = ''
-        character(len=512) :: pr_title = ''
-        logical :: pr_draft = .false.
-    end type branch_metadata
+   use string_utils, only: str, starts_with
+   implicit none
+   private
+
+   public :: json_write_metadata, json_read_metadata, branch_metadata
+
+   type :: branch_metadata
+      character(len=256) :: branch_name = ''
+      character(len=256) :: commit = ''
+      character(len=256) :: timestamp = ''
+      character(len=64) :: run_id = ''
+      character(len=256) :: repo = ''
+      logical :: has_pngs = .false.
+      integer :: diff_count = 0
+      integer :: pr_number = 0
+      character(len=512) :: pr_url = ''
+      character(len=512) :: pr_title = ''
+      logical :: pr_draft = .false.
+   end type branch_metadata
 
 contains
 
-    subroutine json_write_metadata(filepath, branches, n_branches)
+   subroutine json_write_metadata(filepath, branches, n_branches)
     !! Write metadata to JSON file
-        character(len=*), intent(in) :: filepath
-        type(branch_metadata), intent(in) :: branches(:)
-        integer, intent(in) :: n_branches
-        integer :: unit, i
+      character(len=*), intent(in) :: filepath
+      type(branch_metadata), intent(in) :: branches(:)
+      integer, intent(in) :: n_branches
+      integer :: unit, i
 
-        open (newunit=unit, file=trim(filepath), status='replace', action='write')
+      open (newunit=unit, file=trim(filepath), status='replace', action='write')
 
-        write (unit, '(A)') '{'
-        do i = 1, n_branches
-            call write_branch_entry(unit, branches(i), i == n_branches)
-        end do
-        write (unit, '(A)') '}'
+      write (unit, '(A)') '{'
+      do i = 1, n_branches
+         call write_branch_entry(unit, branches(i), i == n_branches)
+      end do
+      write (unit, '(A)') '}'
 
-        close (unit)
-    end subroutine json_write_metadata
+      close (unit)
+   end subroutine json_write_metadata
 
-    subroutine write_branch_entry(unit, branch, is_last)
+   subroutine write_branch_entry(unit, branch, is_last)
     !! Write a single branch entry
-        integer, intent(in) :: unit
-        type(branch_metadata), intent(in) :: branch
-        logical, intent(in) :: is_last
-        character(len=1) :: comma
-
-        if (is_last) then
-            comma = ' '
-        else
-            comma = ','
-        end if
-
-        write (unit, '(A)') '  "'//trim(branch%branch_name)//'": {'
-        write (unit, '(A)') '    "commit": "'//trim(branch%commit)//'",'
-        write (unit, '(A)') '    "has_pngs": '// &
-            merge('true ', 'false', branch%has_pngs)//','
-        write (unit, '(A)') '    "diff_count": '//trim(str(branch%diff_count))//','
-        write (unit, '(A)') '    "path": "'//trim(branch%branch_name)//'",'
-        write (unit, '(A)') '    "repo": "'//trim(branch%repo)//'",'
-        write (unit, '(A)') '    "run_id": "'//trim(branch%run_id)//'",'
-        write (unit, '(A)') '    "updated": "'//trim(branch%timestamp)//'"'
-
-        if (branch%pr_number > 0) then
-            write (unit, '(A)') '    ,'
-            write (unit, '(A)') '    "pr_info": {'
-            write (unit, '(A,I0,A)') '      "number": ', branch%pr_number, ','
-            write (unit, '(A)') '      "url": "'//trim(branch%pr_url)//'",'
-            write (unit, '(A)') '      "title": "'//trim(branch%pr_title)//'",'
+      integer, intent(in) :: unit
+      type(branch_metadata), intent(in) :: branch
+      logical, intent(in) :: is_last
+      character(len=1) :: comma
+
+      if (is_last) then
+         comma = ' '
+      else
+         comma = ','
+      end if
+
+      write (unit, '(A)') '  "'//trim(branch%branch_name)//'": {'
+      write (unit, '(A)') '    "commit": "'//trim(branch%commit)//'",'
+      write (unit, '(A)') '    "has_pngs": '// &
+         merge('true ', 'false', branch%has_pngs)//','
+      write (unit, '(A)') '    "diff_count": '//trim(str(branch%diff_count))//','
+      write (unit, '(A)') '    "path": "'//trim(branch%branch_name)//'",'
+      write (unit, '(A)') '    "repo": "'//trim(branch%repo)//'",'
+      write (unit, '(A)') '    "run_id": "'//trim(branch%run_id)//'",'
+      write (unit, '(A)') '    "updated": "'//trim(branch%timestamp)//'"'
+
+      if (branch%pr_number > 0) then
+         write (unit, '(A)') '    ,'
+         write (unit, '(A)') '    "pr_info": {'
+         write (unit, '(A,I0,A)') '      "number": ', branch%pr_number, ','
+         write (unit, '(A)') '      "url": "'//trim(branch%pr_url)//'",'
+         write (unit, '(A)') '      "title": "'//trim(branch%pr_title)//'",'
          write (unit, '(A)') '      "draft": '//merge('true ', 'false', branch%pr_draft)
-            write (unit, '(A)') '    }'
-        end if
-
-        write (unit, '(A)') '  }'//comma
-    end subroutine write_branch_entry
-
-    subroutine json_read_metadata(filepath, branches, n_branches, max_branches)
-    !! Read metadata from JSON file (simplified parser)
-        character(len=*), intent(in) :: filepath
-        type(branch_metadata), intent(out) :: branches(:)
-        integer, intent(out) :: n_branches
-        integer, intent(in), optional :: max_branches
-        integer :: unit, ios, max_n
-        character(len=2048) :: line
-        logical :: exists
-
-        if (present(max_branches)) then
-            max_n = max_branches
-        else
-            max_n = size(branches)
-        end if
-
-        inquire (file=trim(filepath), exist=exists)
-        if (.not. exists) then
-            n_branches = 0
-            return
-        end if
-
-        n_branches = 0
-        open (newunit=unit, file=trim(filepath), status='old', action='read')
-        do
-            read (unit, '(A)', iostat=ios) line
-            if (ios /= 0) exit
-            if (index(line, '"path":') > 0) n_branches = n_branches + 1
-            if (n_branches >= max_n) exit
-        end do
-        close (unit)
-
-        ! For now, we'll keep this simple and regenerate from scratch
-    end subroutine json_read_metadata
+         write (unit, '(A)') '    }'
+      end if
+
+      write (unit, '(A)') '  }'//comma
+   end subroutine write_branch_entry
+
+   subroutine json_read_metadata(filepath, branches, n_branches, max_branches)
+    !! Read metadata from JSON file written by json_write_metadata
+      character(len=*), intent(in) :: filepath
+      type(branch_metadata), intent(out) :: branches(:)
+      integer, intent(out) :: n_branches
+      integer, intent(in), optional :: max_branches
+      integer :: unit, ios, max_n, current_index
+      character(len=2048) :: line
+      character(len=:), allocatable :: trimmed
+      logical :: exists, in_branch, in_pr_info
+
+      if (present(max_branches)) then
+         max_n = max_branches
+      else
+         max_n = size(branches)
+      end if
+
+      inquire (file=trim(filepath), exist=exists)
+      if (.not. exists) then
+         n_branches = 0
+         return
+      end if
+
+      n_branches = 0
+      current_index = 0
+      in_branch = .false.
+      in_pr_info = .false.
+
+      open (newunit=unit, file=trim(filepath), status='old', action='read')
+      do
+         read (unit, '(A)', iostat=ios) line
+         if (ios /= 0) exit
+
+         trimmed = adjustl(trim(line))
+
+         if (.not. in_branch) then
+            if (is_branch_header(trimmed)) then
+               if (n_branches >= max_n) exit
+               n_branches = n_branches + 1
+               current_index = n_branches
+               branches(current_index) = branch_metadata()
+               call parse_branch_name(trimmed, branches(current_index)%branch_name)
+               in_branch = .true.
+            end if
+            cycle
+         end if
+
+         if (.not. in_pr_info .and. starts_with(trimmed, '"pr_info"')) then
+            in_pr_info = .true.
+            cycle
+         end if
+
+         if (in_pr_info) then
+            if (is_section_end(trimmed)) then
+               in_pr_info = .false.
+               cycle
+            end if
+            call parse_pr_field(trimmed, branches(current_index))
+            cycle
+         end if
+
+         if (is_section_end(trimmed)) then
+            in_branch = .false.
+            current_index = 0
+            cycle
+         end if
+
+         call parse_branch_field(trimmed, branches(current_index))
+      end do
+      close (unit)
+
+      if (n_branches > max_n) n_branches = max_n
+   end subroutine json_read_metadata
+
+   logical function is_branch_header(line) result(header)
+      character(len=*), intent(in) :: line
+
+      header = (index(line, '": {') > 0 .and. index(line, '"pr_info"') == 0 .and. &
+                index(line, '{') > 0)
+   end function is_branch_header
+
+   logical function is_section_end(line) result(ended)
+      character(len=*), intent(in) :: line
+
+      ended = (trim(line) == '}' .or. trim(line) == '},' .or. trim(line) == '}'//char(0))
+   end function is_section_end
+
+   subroutine parse_branch_name(line, name)
+      character(len=*), intent(in) :: line
+      character(len=*), intent(inout) :: name
+      integer :: first_quote, second_quote
+
+      first_quote = index(line, '"')
+      if (first_quote <= 0) then
+         name = ''
+         return
+      end if
+
+      second_quote = index(line(first_quote + 1:), '"')
+      if (second_quote <= 0) then
+         name = ''
+         return
+      end if
+
+      name = line(first_quote + 1:first_quote + second_quote - 1)
+   end subroutine parse_branch_name
+
+   subroutine parse_branch_field(line, branch)
+      character(len=*), intent(in) :: line
+      type(branch_metadata), intent(inout) :: branch
+      character(len=512) :: value
+      integer :: number, ios
+      logical :: logical_value
+
+      if (extract_json_string(line, '"commit"', value)) then
+         branch%commit = trim(value)
+      else if (extract_json_string(line, '"path"', value)) then
+         branch%branch_name = trim(value)
+      else if (extract_json_string(line, '"repo"', value)) then
+         branch%repo = trim(value)
+      else if (extract_json_string(line, '"run_id"', value)) then
+         branch%run_id = trim(value)
+      else if (extract_json_string(line, '"updated"', value)) then
+         branch%timestamp = trim(value)
+      else if (extract_json_integer(line, '"diff_count"', number)) then
+         branch%diff_count = number
+      else if (extract_json_integer(line, '"diff"', number)) then
+         branch%diff_count = number
+      else if (extract_json_logical(line, '"has_pngs"', logical_value)) then
+         branch%has_pngs = logical_value
+      end if
+   end subroutine parse_branch_field
+
+   subroutine parse_pr_field(line, branch)
+      character(len=*), intent(in) :: line
+      type(branch_metadata), intent(inout) :: branch
+      character(len=512) :: value
+      integer :: number
+      logical :: logical_value
+
+      if (extract_json_integer(line, '"number"', number)) then
+         branch%pr_number = number
+      else if (extract_json_string(line, '"url"', value)) then
+         branch%pr_url = trim(value)
+      else if (extract_json_string(line, '"title"', value)) then
+         branch%pr_title = trim(value)
+      else if (extract_json_logical(line, '"draft"', logical_value)) then
+         branch%pr_draft = logical_value
+      end if
+   end subroutine parse_pr_field
+
+   logical function extract_json_string(line, field, value) result(found)
+      character(len=*), intent(in) :: line
+      character(len=*), intent(in) :: field
+      character(len=*), intent(out) :: value
+      integer :: pos, first_quote, second_quote, colon_pos
+
+      value = ''
+      pos = index(line, field)
+      if (pos == 0) then
+         found = .false.
+         return
+      end if
+
+      colon_pos = index(line(pos:), ':')
+      if (colon_pos == 0) then
+         found = .false.
+         return
+      end if
+      pos = pos + colon_pos - 1
+
+      first_quote = index(line(pos + 1:), '"')
+      if (first_quote == 0) then
+         found = .false.
+         return
+      end if
+      first_quote = pos + first_quote
+      second_quote = index(line(first_quote + 1:), '"')
+      if (second_quote == 0) then
+         found = .false.
+         return
+      end if
+      second_quote = first_quote + second_quote
+
+      value = line(first_quote + 1:second_quote - 1)
+      found = .true.
+   end function extract_json_string
+
+   logical function extract_json_integer(line, field, value) result(found)
+      character(len=*), intent(in) :: line
+      character(len=*), intent(in) :: field
+      integer, intent(out) :: value
+      integer :: pos, colon_pos, ios
+      character(len=256) :: buffer
+
+      value = 0
+      pos = index(line, field)
+      if (pos == 0) then
+         found = .false.
+         return
+      end if
+
+      colon_pos = index(line(pos:), ':')
+      if (colon_pos == 0) then
+         found = .false.
+         return
+      end if
+
+      colon_pos = pos + colon_pos - 1
+
+      buffer = adjustl(trim(line(colon_pos + 1:)))
+      call strip_trailing_comma(buffer)
+      read (buffer, *, iostat=ios) value
+      found = (ios == 0)
+   end function extract_json_integer
+
+   logical function extract_json_logical(line, field, value) result(found)
+      character(len=*), intent(in) :: line
+      character(len=*), intent(in) :: field
+      logical, intent(out) :: value
+      integer :: pos, colon_pos, ios
+      character(len=256) :: buffer
+
+      value = .false.
+      pos = index(line, field)
+      if (pos == 0) then
+         found = .false.
+         return
+      end if
+
+      colon_pos = index(line(pos:), ':')
+      if (colon_pos == 0) then
+         found = .false.
+         return
+      end if
+
+      colon_pos = pos + colon_pos - 1
+
+      buffer = adjustl(trim(line(colon_pos + 1:)))
+      call strip_trailing_comma(buffer)
+      read (buffer, *, iostat=ios) value
+      found = (ios == 0)
+   end function extract_json_logical
+
+   subroutine strip_trailing_comma(text)
+      character(len=*), intent(inout) :: text
+      integer :: len_trimmed
+
+      len_trimmed = len_trim(text)
+      if (len_trimmed <= 0) return
+      if (text(len_trimmed:len_trimmed) == ',') then
+         text(len_trimmed:len_trimmed) = ' '
+      end if
+   end subroutine strip_trailing_comma
 
 end module json_utils
diff --git a/test/test_integration.f90 b/test/test_integration.f90
index 99bd8e1..78b4574 100644
--- a/test/test_integration.f90
+++ b/test/test_integration.f90
@@ -1,323 +1,459 @@
 program test_integration
   !! Integration tests - test dashboard generation with mock data
-    use dashboard
-    use file_utils
-    implicit none
-
-    integer :: num_tests, num_passed
-    integer, parameter :: basic_png_bytes(68) = [integer :: &
+   use dashboard
+   use file_utils
+   use iso_c_binding, only: c_char, c_null_char, c_int
+   implicit none
+
+   integer :: num_tests, num_passed
+   integer, parameter :: basic_png_bytes(68) = [integer :: &
+                                                137, 80, 78, 71, 13, 10, 26, 10, &
+                                                0, 0, 0, 13, 73, 72, 68, 82, &
+                                                0, 0, 0, 1, 0, 0, 0, 1, &
+                                                8, 4, 0, 0, 0, 181, 28, 12, &
+                                                2, 0, 0, 0, 11, 73, 68, 65, &
+                                                84, 120, 218, 99, 252, 255, 31, 0, &
+                                                3, 3, 2, 0, 238, 103, 208, 90, &
+                                                0, 0, 0, 0, 73, 69, 78, 68, &
+                                                174, 66, 96, 130]
+   integer, parameter :: fancy_png_bytes(104) = [integer :: &
                                                  137, 80, 78, 71, 13, 10, 26, 10, &
                                                  0, 0, 0, 13, 73, 72, 68, 82, &
-                                                 0, 0, 0, 1, 0, 0, 0, 1, &
-                                                 8, 4, 0, 0, 0, 181, 28, 12, &
-                                                 2, 0, 0, 0, 11, 73, 68, 65, &
-                                                 84, 120, 218, 99, 252, 255, 31, 0, &
-                                                 3, 3, 2, 0, 238, 103, 208, 90, &
-                                                 0, 0, 0, 0, 73, 69, 78, 68, &
-                                                 174, 66, 96, 130]
-    integer, parameter :: fancy_png_bytes(104) = [integer :: &
-                                                  137, 80, 78, 71, 13, 10, 26, 10, &
-                                                  0, 0, 0, 13, 73, 72, 68, 82, &
-                                                  0, 0, 0, 32, 0, 0, 0, 32, &
-                                                  8, 6, 0, 0, 0, 115, 122, 122, &
-                                                  244, 0, 0, 0, 47, 73, 68, 65, &
-                                                  84, 120, 156, 237, 206, 49, 1, 0, &
-                                                  48, 12, 128, 48, 54, 255, 158, 91, &
-                                                  25, 125, 130, 1, 242, 166, 166, 195, &
-                                                  254, 229, 28, 0, 0, 0, 0, 0, &
-                                                  0, 0, 0, 0, 0, 0, 0, 0, &
-                                                  0, 160, 106, 1, 48, 227, 2, 62, &
-                                                  54, 153, 94, 177, 0, 0, 0, 0, &
-                                                  73, 69, 78, 68, 174, 66, 96, 130]
-    logical :: success
-
-    num_tests = 0
-    num_passed = 0
-
-    call test_dashboard_generation()
-    call test_multiple_branches()
-    call test_nested_branch_gallery()
-    call test_diff_detection()
-
-    print *, ''
-    print *, 'Integration Tests: ', num_passed, '/', num_tests, ' passed'
-
-    if (num_passed /= num_tests) then
-        stop 1
-    end if
+                                                 0, 0, 0, 32, 0, 0, 0, 32, &
+                                                 8, 6, 0, 0, 0, 115, 122, 122, &
+                                                 244, 0, 0, 0, 47, 73, 68, 65, &
+                                                 84, 120, 156, 237, 206, 49, 1, 0, &
+                                                 48, 12, 128, 48, 54, 255, 158, 91, &
+                                                 25, 125, 130, 1, 242, 166, 166, 195, &
+                                                 254, 229, 28, 0, 0, 0, 0, 0, &
+                                                 0, 0, 0, 0, 0, 0, 0, 0, &
+                                                 0, 160, 106, 1, 48, 227, 2, 62, &
+                                                 54, 153, 94, 177, 0, 0, 0, 0, &
+                                                 73, 69, 78, 68, 174, 66, 96, 130]
+   interface
+      function c_setenv(name, value, overwrite) bind(C, name="setenv") &
+         result(ret)
+         use iso_c_binding, only: c_char, c_int
+         character(kind=c_char), dimension(*), intent(in) :: name
+         character(kind=c_char), dimension(*), intent(in) :: value
+         integer(c_int), value :: overwrite
+         integer(c_int) :: ret
+      end function c_setenv
+
+      function c_unsetenv(name) bind(C, name="unsetenv") result(ret)
+         use iso_c_binding, only: c_char, c_int
+         character(kind=c_char), dimension(*), intent(in) :: name
+         integer(c_int) :: ret
+      end function c_unsetenv
+   end interface
+   logical :: success
+
+   num_tests = 0
+   num_passed = 0
+
+   call test_dashboard_generation()
+   call test_multiple_branches()
+   call test_nested_branch_gallery()
+   call test_diff_detection()
+   call test_pr_ref_branch()
+
+   print *, ''
+   print *, 'Integration Tests: ', num_passed, '/', num_tests, ' passed'
+
+   if (num_passed /= num_tests) then
+      stop 1
+   end if
 
 contains
 
-    subroutine test_dashboard_generation()
-        type(dashboard_config) :: config
-        logical :: exists
-
-        num_tests = num_tests + 1
-
-        ! Setup test config
-        config%image_root = 'test_artifacts'
-        config%output_dir = 'test_output'
-        config%branch_name = 'test-branch'
-        config%commit_sha = 'abc123def456'
-        config%run_id = '12345'
-        config%repo = 'test-org/test-repo'
-        config%project_name = 'Test Project'
-
-        ! Create mock image directory (empty for this test)
-        call create_directory(config%image_root, success)
-
-        ! Generate dashboard
-        call generate_dashboard(config, success)
-
-        if (success .and. &
-            file_exists(trim(config%output_dir)//'/test/test-branch/index.html') .and. &
-            file_exists(trim(config%output_dir)//'/test/test-branch/diff.html') .and. &
-            file_exists(trim(config%output_dir)//'/test/index.html') .and. &
-            file_exists(trim(config%output_dir)//'/index.html')) then
-            num_passed = num_passed + 1
-            print *, '[PASS] dashboard_generation: creates all files'
-        else
-            print *, '[FAIL] dashboard_generation: creates all files'
-            print *, '  Success: ', success
-            print *, '  Branch page: ', &
-                file_exists(trim(config%output_dir)//'/test/test-branch/index.html')
-            print *, '  Diff page: ', &
-                file_exists(trim(config%output_dir)//'/test/test-branch/diff.html')
-            print *, '  Overview page: ', &
-                file_exists(trim(config%output_dir)//'/test/index.html')
-            print *, '  Root page: ', &
-                file_exists(trim(config%output_dir)//'/index.html')
-        end if
-
-        ! Cleanup
-        call remove_directory(config%image_root, success)
-        call remove_directory(config%output_dir, success)
-    end subroutine test_dashboard_generation
-
-    subroutine test_multiple_branches()
-        type(dashboard_config) :: config
-        logical :: exists
-
-        num_tests = num_tests + 1
-
-        ! Setup test config
-        config%image_root = 'test_artifacts'
-        config%output_dir = 'test_output'
-        config%repo = 'test-org/test-repo'
-        config%project_name = 'Test Project'
-
-        call create_directory(config%image_root, success)
-
-        ! Generate dashboard for branch 1
-        config%branch_name = 'main'
-        config%commit_sha = 'abc123'
-        config%run_id = '11111'
-        call generate_dashboard(config, success)
-
-        ! Generate dashboard for branch 2
-        config%branch_name = 'feature'
-        config%commit_sha = 'def456'
-        config%run_id = '22222'
-        call generate_dashboard(config, success)
-
-        ! Check both branches exist
-        if (success .and. &
-            file_exists(trim(config%output_dir)//'/test/main/index.html') .and. &
-            file_exists(trim(config%output_dir)//'/test/main/diff.html') .and. &
-            file_exists(trim(config%output_dir)//'/test/feature/index.html') .and. &
-            file_exists(trim(config%output_dir)//'/test/feature/diff.html') .and. &
-            file_exists(trim(config%output_dir)//'/test/branches.json')) then
-            num_passed = num_passed + 1
-            print *, '[PASS] multiple_branches: both branches exist'
-        else
-            print *, '[FAIL] multiple_branches: both branches exist'
-        end if
-
-        ! Cleanup
-        call remove_directory(config%image_root, success)
-        call remove_directory(config%output_dir, success)
-    end subroutine test_multiple_branches
-
-    subroutine test_nested_branch_gallery()
-        type(dashboard_config) :: config
-        character(len=:), allocatable :: branch_dir, branch_file
-        character(len=:), allocatable :: fancy_file, basic_file
-      logical :: run_success, fancy_exists, basic_exists, link_ok, style_ok, diff_nav_ok
-        integer :: unit, ios
-        character(len=1024) :: line
-
-        num_tests = num_tests + 1
-
-        config%image_root = 'test_artifacts'
-        config%output_dir = 'test_output'
-        config%branch_name = 'feat/support-png-jpg-images'
-        config%commit_sha = 'feedfacecafebeef'
-        config%run_id = '33333'
-        config%repo = 'test-org/test-repo'
-        config%project_name = 'Test Project'
-
-        call create_directory(trim(config%image_root)//'/basic', run_success)
-        call create_directory(trim(config%image_root)//'/fancy', run_success)
-
-        call write_png_fixture(trim(config%image_root)//'/basic/chart.png', &
-                               basic_png_bytes)
-        call write_png_fixture(trim(config%image_root)//'/fancy/chart.PNG', &
-                               fancy_png_bytes)
-
-        call generate_dashboard(config, run_success)
-
-        branch_dir = trim(config%output_dir)//'/test/feat/support-png-jpg-images'
-        branch_file = trim(branch_dir)//'/index.html'
-        fancy_file = trim(branch_dir)//'/images/fancy/chart.PNG'
-        basic_file = trim(branch_dir)//'/images/basic/chart.png'
-
-        fancy_exists = file_exists(fancy_file)
-        basic_exists = file_exists(basic_file)
-
-        link_ok = .false.
-        style_ok = .false.
-        diff_nav_ok = .false.
-        open (newunit=unit, file=branch_file, status='old', action='read', iostat=ios)
-        if (ios == 0) then
-            do
-                read (unit, '(A)', iostat=ios) line
-                if (ios /= 0) exit
-                if (index(line, 'href="../../index.html"') > 0) link_ok = .true.
-                if (index(line, 'class="diff-link"') > 0) diff_nav_ok = .true.
-                if (index(line, 'gallery-item diff') > 0) style_ok = .true.
-                if (link_ok .and. style_ok .and. diff_nav_ok) exit
-            end do
-            close (unit)
-        end if
-
-        if (run_success .and. fancy_exists .and. basic_exists .and. link_ok .and. &
-            style_ok .and. diff_nav_ok) then
-            num_passed = num_passed + 1
-            print *, '[PASS] nested_branch_gallery: preserves fancy outputs and link'
-        else
-            print *, '[FAIL] nested_branch_gallery: preserves fancy outputs and link'
-            print *, '  Success: ', run_success
-            print *, '  Fancy exists: ', fancy_exists
-            print *, '  Basic exists: ', basic_exists
-            print *, '  Back link ok: ', link_ok
-            print *, '  Diff nav ok: ', diff_nav_ok
-            print *, '  Diff highlight ok: ', style_ok
-        end if
-
-        call remove_directory(config%image_root, run_success)
-        call remove_directory(config%output_dir, run_success)
-    end subroutine test_nested_branch_gallery
-
-    subroutine test_diff_detection()
-        type(dashboard_config) :: config
-    character(len=:), allocatable :: feature_dir, diff_file, gallery_file, overview_file
-        logical :: run_success, diff_exists, highlight_found, diff_link_found
-        logical :: diff_page_has_image, diff_count_ok
-        integer :: unit, ios
-        character(len=1024) :: line
-
-        num_tests = num_tests + 1
-
-        config%image_root = 'test_artifacts'
-        config%output_dir = 'test_output'
-        config%repo = 'test-org/test-repo'
-        config%project_name = 'Test Project'
-        config%base_branch = 'main'
-
-        call create_directory(config%image_root, run_success)
-
-        config%branch_name = 'main'
-        config%commit_sha = 'aaa111'
-        config%run_id = '44444'
-        call write_png_fixture(trim(config%image_root)//'/chart.png', basic_png_bytes)
-        call generate_dashboard(config, run_success)
-
-        config%branch_name = 'feature-diff'
-        config%commit_sha = 'bbb222'
-        config%run_id = '55555'
-        call write_png_fixture(trim(config%image_root)//'/chart.png', fancy_png_bytes)
-        call generate_dashboard(config, run_success)
-
-        feature_dir = trim(config%output_dir)//'/test/feature-diff'
-        diff_file = trim(feature_dir)//'/diff.html'
-        gallery_file = trim(feature_dir)//'/index.html'
-        overview_file = trim(config%output_dir)//'/test/index.html'
-
-        diff_exists = file_exists(diff_file)
-        highlight_found = .false.
-        diff_link_found = .false.
-        diff_page_has_image = .false.
-        diff_count_ok = .false.
-
-        open (newunit=unit, file=gallery_file, status='old', action='read', iostat=ios)
-        if (ios == 0) then
-            do
-                read (unit, '(A)', iostat=ios) line
-                if (ios /= 0) exit
-                if (index(line, 'gallery-item diff') > 0) highlight_found = .true.
-            end do
-            close (unit)
-        end if
-
-        open (newunit=unit, file=overview_file, status='old', action='read', iostat=ios)
-        if (ios == 0) then
-            do
-                read (unit, '(A)', iostat=ios) line
-                if (ios /= 0) exit
-                if (index(line, 'feature-diff/diff.html') > 0) then
-                    diff_link_found = .true.
-                    if (index(line, 'diff</a> (1)') > 0) diff_count_ok = .true.
-                end if
-            end do
-            close (unit)
-        end if
-
-        open (newunit=unit, file=diff_file, status='old', action='read', iostat=ios)
-        if (ios == 0) then
+   function to_c_string(str) result(buffer)
+      character(len=*), intent(in) :: str
+      character(kind=c_char), allocatable :: buffer(:)
+      integer :: n, i
+
+      n = len_trim(str)
+      allocate (buffer(1:max(1, n + 1)))
+      if (n > 0) then
+         do i = 1, n
+            buffer(i) = char(iachar(str(i:i)), kind=c_char)
+         end do
+         buffer(n + 1) = c_null_char
+      else
+         buffer(1) = c_null_char
+      end if
+   end function to_c_string
+
+   subroutine set_env(name, value)
+      character(len=*), intent(in) :: name, value
+      character(kind=c_char), allocatable :: name_c(:), value_c(:)
+      integer(c_int) :: ret
+
+      name_c = to_c_string(name)
+      value_c = to_c_string(value)
+      ret = c_setenv(name_c, value_c, 1_c_int)
+   end subroutine set_env
+
+   subroutine clear_env(name)
+      character(len=*), intent(in) :: name
+      character(kind=c_char), allocatable :: name_c(:)
+      integer(c_int) :: ret
+
+      name_c = to_c_string(name)
+      ret = c_unsetenv(name_c)
+   end subroutine clear_env
+
+   subroutine test_dashboard_generation()
+      type(dashboard_config) :: config
+      logical :: exists
+
+      num_tests = num_tests + 1
+
+      ! Setup test config
+      config%image_root = 'test_artifacts'
+      config%output_dir = 'test_output'
+      config%branch_name = 'test-branch'
+      config%commit_sha = 'abc123def456'
+      config%run_id = '12345'
+      config%repo = 'test-org/test-repo'
+      config%project_name = 'Test Project'
+
+      ! Create mock image directory (empty for this test)
+      call create_directory(config%image_root, success)
+
+      ! Generate dashboard
+      call generate_dashboard(config, success)
+
+      if (success .and. &
+          file_exists(trim(config%output_dir)//'/test/test-branch/index.html') .and. &
+          file_exists(trim(config%output_dir)//'/test/test-branch/diff.html') .and. &
+          file_exists(trim(config%output_dir)//'/test/index.html') .and. &
+          file_exists(trim(config%output_dir)//'/index.html')) then
+         num_passed = num_passed + 1
+         print *, '[PASS] dashboard_generation: creates all files'
+      else
+         print *, '[FAIL] dashboard_generation: creates all files'
+         print *, '  Success: ', success
+         print *, '  Branch page: ', &
+            file_exists(trim(config%output_dir)//'/test/test-branch/index.html')
+         print *, '  Diff page: ', &
+            file_exists(trim(config%output_dir)//'/test/test-branch/diff.html')
+         print *, '  Overview page: ', &
+            file_exists(trim(config%output_dir)//'/test/index.html')
+         print *, '  Root page: ', &
+            file_exists(trim(config%output_dir)//'/index.html')
+      end if
+
+      ! Cleanup
+      call remove_directory(config%image_root, success)
+      call remove_directory(config%output_dir, success)
+   end subroutine test_dashboard_generation
+
+   subroutine test_multiple_branches()
+      type(dashboard_config) :: config
+      logical :: main_found, feature_found
+      integer :: unit_meta, ios
+      character(len=1024) :: meta_line
+
+      num_tests = num_tests + 1
+
+      ! Setup test config
+      config%image_root = 'test_artifacts'
+      config%output_dir = 'test_output'
+      config%repo = 'test-org/test-repo'
+      config%project_name = 'Test Project'
+
+      call create_directory(config%image_root, success)
+
+      ! Generate dashboard for branch 1
+      config%branch_name = 'main'
+      config%commit_sha = 'abc123'
+      config%run_id = '11111'
+      call generate_dashboard(config, success)
+
+      ! Generate dashboard for branch 2
+      config%branch_name = 'feature'
+      config%commit_sha = 'def456'
+      config%run_id = '22222'
+      call generate_dashboard(config, success)
+
+      ! Check both branches exist
+      main_found = .false.
+      feature_found = .false.
+      if (file_exists(trim(config%output_dir)//'/test/branches.json')) then
+         open (newunit=unit_meta, file=trim(config%output_dir)//'/test/branches.json', &
+               status='old', action='read', iostat=ios)
+         if (ios == 0) then
             do
-                read (unit, '(A)', iostat=ios) line
-                if (ios /= 0) exit
-                if (index(line, '<img') > 0) then
-                    diff_page_has_image = .true.
-                    exit
-                end if
+               read (unit_meta, '(A)', iostat=ios) meta_line
+               if (ios /= 0) exit
+               if (index(meta_line, '"main"') > 0) main_found = .true.
+               if (index(meta_line, '"feature"') > 0) feature_found = .true.
+               if (main_found .and. feature_found) exit
             end do
-            close (unit)
-        end if
-
-        if (diff_exists .and. highlight_found .and. diff_link_found .and. diff_page_has_image .and. diff_count_ok) then
-            num_passed = num_passed + 1
-            print *, '[PASS] diff_detection: highlights differing artifacts'
-        else
-            print *, '[FAIL] diff_detection: highlights differing artifacts'
-            print *, '  diff page exists: ', diff_exists
-            print *, '  gallery highlights diff: ', highlight_found
-            print *, '  overview diff link: ', diff_link_found
-            print *, '  diff page shows image: ', diff_page_has_image
-            print *, '  diff count shown: ', diff_count_ok
-        end if
-
-        call remove_directory(config%image_root, run_success)
-        call remove_directory(config%output_dir, run_success)
-    end subroutine test_diff_detection
-
-    subroutine write_png_fixture(path, data)
-        character(len=*), intent(in) :: path
-        integer, intent(in) :: data(:)
-        integer :: unit, ios, i
-        character(len=1) :: ch
-
-        open (newunit=unit, file=trim(path), status='replace', access='stream', &
-              form='unformatted', action='write', iostat=ios)
-        if (ios /= 0) return
-
-        do i = 1, size(data)
-            ch = achar(data(i))
-            write (unit, iostat=ios) ch
+            close (unit_meta)
+         end if
+      end if
+
+      if (success .and. &
+          file_exists(trim(config%output_dir)//'/test/main/index.html') .and. &
+          file_exists(trim(config%output_dir)//'/test/main/diff.html') .and. &
+          file_exists(trim(config%output_dir)//'/test/feature/index.html') .and. &
+          file_exists(trim(config%output_dir)//'/test/feature/diff.html') .and. &
+          file_exists(trim(config%output_dir)//'/test/branches.json') .and. &
+          main_found .and. feature_found) then
+         num_passed = num_passed + 1
+         print *, '[PASS] multiple_branches: both branches exist'
+      else
+         print *, '[FAIL] multiple_branches: both branches exist'
+         print *, '  Metadata main: ', main_found
+         print *, '  Metadata feature: ', feature_found
+      end if
+
+      ! Cleanup
+      call remove_directory(config%image_root, success)
+      call remove_directory(config%output_dir, success)
+   end subroutine test_multiple_branches
+
+   subroutine test_nested_branch_gallery()
+      type(dashboard_config) :: config
+      character(len=:), allocatable :: branch_dir, branch_file
+      character(len=:), allocatable :: fancy_file, basic_file
+      logical :: run_success, fancy_exists, basic_exists, link_ok, style_ok, diff_nav_ok
+      integer :: unit, ios
+      character(len=1024) :: line
+
+      num_tests = num_tests + 1
+
+      config%image_root = 'test_artifacts'
+      config%output_dir = 'test_output'
+      config%branch_name = 'feat/support-png-jpg-images'
+      config%commit_sha = 'feedfacecafebeef'
+      config%run_id = '33333'
+      config%repo = 'test-org/test-repo'
+      config%project_name = 'Test Project'
+
+      call create_directory(trim(config%image_root)//'/basic', run_success)
+      call create_directory(trim(config%image_root)//'/fancy', run_success)
+
+      call write_png_fixture(trim(config%image_root)//'/basic/chart.png', &
+                             basic_png_bytes)
+      call write_png_fixture(trim(config%image_root)//'/fancy/chart.PNG', &
+                             fancy_png_bytes)
+
+      call generate_dashboard(config, run_success)
+
+      branch_dir = trim(config%output_dir)//'/test/feat/support-png-jpg-images'
+      branch_file = trim(branch_dir)//'/index.html'
+      fancy_file = trim(branch_dir)//'/images/fancy/chart.PNG'
+      basic_file = trim(branch_dir)//'/images/basic/chart.png'
+
+      fancy_exists = file_exists(fancy_file)
+      basic_exists = file_exists(basic_file)
+
+      link_ok = .false.
+      style_ok = .false.
+      diff_nav_ok = .false.
+      open (newunit=unit, file=branch_file, status='old', action='read', iostat=ios)
+      if (ios == 0) then
+         do
+            read (unit, '(A)', iostat=ios) line
             if (ios /= 0) exit
-        end do
-
-        close (unit)
-    end subroutine write_png_fixture
+            if (index(line, 'href="../../index.html"') > 0) link_ok = .true.
+            if (index(line, 'class="diff-link"') > 0) diff_nav_ok = .true.
+            if (index(line, 'gallery-item diff') > 0) style_ok = .true.
+            if (link_ok .and. style_ok .and. diff_nav_ok) exit
+         end do
+         close (unit)
+      end if
+
+      if (run_success .and. fancy_exists .and. basic_exists .and. link_ok .and. &
+          style_ok .and. diff_nav_ok) then
+         num_passed = num_passed + 1
+         print *, '[PASS] nested_branch_gallery: preserves fancy outputs and link'
+      else
+         print *, '[FAIL] nested_branch_gallery: preserves fancy outputs and link'
+         print *, '  Success: ', run_success
+         print *, '  Fancy exists: ', fancy_exists
+         print *, '  Basic exists: ', basic_exists
+         print *, '  Back link ok: ', link_ok
+         print *, '  Diff nav ok: ', diff_nav_ok
+         print *, '  Diff highlight ok: ', style_ok
+      end if
+
+      call remove_directory(config%image_root, run_success)
+      call remove_directory(config%output_dir, run_success)
+   end subroutine test_nested_branch_gallery
+
+   subroutine test_diff_detection()
+      type(dashboard_config) :: config
+      character(len=:), allocatable :: feature_dir, diff_file, gallery_file, overview_file
+      logical :: run_success, diff_exists, highlight_found, diff_link_found
+      logical :: diff_page_has_image, diff_count_ok
+      integer :: unit, ios
+      character(len=1024) :: line
+
+      num_tests = num_tests + 1
+
+      config%image_root = 'test_artifacts'
+      config%output_dir = 'test_output'
+      config%repo = 'test-org/test-repo'
+      config%project_name = 'Test Project'
+      config%base_branch = 'main'
+
+      call create_directory(config%image_root, run_success)
+
+      config%branch_name = 'main'
+      config%commit_sha = 'aaa111'
+      config%run_id = '44444'
+      call write_png_fixture(trim(config%image_root)//'/chart.png', basic_png_bytes)
+      call generate_dashboard(config, run_success)
+
+      config%branch_name = 'feature-diff'
+      config%commit_sha = 'bbb222'
+      config%run_id = '55555'
+      call write_png_fixture(trim(config%image_root)//'/chart.png', fancy_png_bytes)
+      call generate_dashboard(config, run_success)
+
+      feature_dir = trim(config%output_dir)//'/test/feature-diff'
+      diff_file = trim(feature_dir)//'/diff.html'
+      gallery_file = trim(feature_dir)//'/index.html'
+      overview_file = trim(config%output_dir)//'/test/index.html'
+
+      diff_exists = file_exists(diff_file)
+      highlight_found = .false.
+      diff_link_found = .false.
+      diff_page_has_image = .false.
+      diff_count_ok = .false.
+
+      open (newunit=unit, file=gallery_file, status='old', action='read', iostat=ios)
+      if (ios == 0) then
+         do
+            read (unit, '(A)', iostat=ios) line
+            if (ios /= 0) exit
+            if (index(line, 'gallery-item diff') > 0) highlight_found = .true.
+         end do
+         close (unit)
+      end if
+
+      open (newunit=unit, file=overview_file, status='old', action='read', iostat=ios)
+      if (ios == 0) then
+         do
+            read (unit, '(A)', iostat=ios) line
+            if (ios /= 0) exit
+            if (index(line, 'feature-diff/diff.html') > 0) then
+               diff_link_found = .true.
+               if (index(line, 'diff</a> (1)') > 0) diff_count_ok = .true.
+            end if
+         end do
+         close (unit)
+      end if
+
+      open (newunit=unit, file=diff_file, status='old', action='read', iostat=ios)
+      if (ios == 0) then
+         do
+            read (unit, '(A)', iostat=ios) line
+            if (ios /= 0) exit
+            if (index(line, '<img') > 0) then
+               diff_page_has_image = .true.
+               exit
+            end if
+         end do
+         close (unit)
+      end if
+
+      if (diff_exists .and. highlight_found .and. diff_link_found .and. diff_page_has_image .and. diff_count_ok) then
+         num_passed = num_passed + 1
+         print *, '[PASS] diff_detection: highlights differing artifacts'
+      else
+         print *, '[FAIL] diff_detection: highlights differing artifacts'
+         print *, '  diff page exists: ', diff_exists
+         print *, '  gallery highlights diff: ', highlight_found
+         print *, '  overview diff link: ', diff_link_found
+         print *, '  diff page shows image: ', diff_page_has_image
+         print *, '  diff count shown: ', diff_count_ok
+      end if
+
+      call remove_directory(config%image_root, run_success)
+      call remove_directory(config%output_dir, run_success)
+   end subroutine test_diff_detection
+
+   subroutine test_pr_ref_branch()
+      type(dashboard_config) :: config
+      character(len=:), allocatable :: overview_file
+      logical :: run_success, pr_link_found
+      integer :: unit, ios
+      character(len=1024) :: line
+
+      num_tests = num_tests + 1
+
+      config%image_root = 'test_artifacts'
+      config%output_dir = 'test_output'
+      config%branch_name = 'feature/graphics'
+      config%commit_sha = 'c0ffee'
+      config%run_id = '99999'
+      config%repo = 'test-org/test-repo'
+      config%project_name = 'Test Project'
+
+      call set_env('GITHUB_REF', 'refs/pull/101/merge')
+      call set_env('GITHUB_PR_NUMBER', '101')
+      call set_env('GITHUB_PR_TITLE', 'Improve shading')
+      call set_env('GITHUB_PR_DRAFT', 'false')
+      call set_env('GITHUB_HEAD_REF', trim(config%branch_name))
+
+      call create_directory(config%image_root, run_success)
+      call generate_dashboard(config, run_success)
+
+      overview_file = trim(config%output_dir)//'/test/index.html'
+      pr_link_found = .false.
+
+      open (newunit=unit, file=overview_file, status='old', action='read', iostat=ios)
+      if (ios == 0) then
+         do
+            read (unit, '(A)', iostat=ios) line
+            if (ios /= 0) exit
+            if (index(line, 'pull/101') > 0) then
+               pr_link_found = .true.
+               exit
+            end if
+         end do
+         close (unit)
+      end if
+
+      if (run_success .and. pr_link_found) then
+         num_passed = num_passed + 1
+         print *, '[PASS] pr_ref_branch: adds PR link for refs/pull branch'
+      else
+         print *, '[FAIL] pr_ref_branch: adds PR link for refs/pull branch'
+         print *, '  Success: ', run_success
+         print *, '  Overview found: ', pr_link_found
+      end if
+
+      call remove_directory(config%image_root, run_success)
+      call remove_directory(config%output_dir, run_success)
+      call clear_env('GITHUB_REF')
+      call clear_env('GITHUB_PR_NUMBER')
+      call clear_env('GITHUB_PR_TITLE')
+      call clear_env('GITHUB_PR_DRAFT')
+      call clear_env('GITHUB_HEAD_REF')
+   end subroutine test_pr_ref_branch
+
+   subroutine write_png_fixture(path, data)
+      character(len=*), intent(in) :: path
+      integer, intent(in) :: data(:)
+      integer :: unit, ios, i
+      character(len=1) :: ch
+
+      open (newunit=unit, file=trim(path), status='replace', access='stream', &
+            form='unformatted', action='write', iostat=ios)
+      if (ios /= 0) return
+
+      do i = 1, size(data)
+         ch = achar(data(i))
+         write (unit, iostat=ios) ch
+         if (ios /= 0) exit
+      end do
+
+      close (unit)
+   end subroutine write_png_fixture
 
 end program test_integration