diff --git a/tracker/tracker_constants.py b/tracker/tracker_constants.py
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+++ b/tracker/tracker_constants.py
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+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Some constants used in Monorail issue tracker pages."""
+from __future__ import print_function
+from __future__ import division
+from __future__ import absolute_import
+
+import re
+
+from proto import user_pb2
+
+
+# Default columns shown on issue list page, and other built-in cols.
+DEFAULT_COL_SPEC = 'ID Type Status Priority Milestone Owner Summary'
+OTHER_BUILT_IN_COLS = [
+    'AllLabels', 'Attachments', 'Stars', 'Opened', 'Closed', 'Modified',
+    'BlockedOn', 'Blocking', 'Blocked', 'MergedInto',
+    'Reporter', 'Cc', 'Project', 'Component',
+    'OwnerModified', 'StatusModified', 'ComponentModified',
+    'OwnerLastVisit']
+
+# These are label prefixes that would conflict with built-in column names.
+# E.g., no issue should have a *label* id-1234 or status-foo because any
+# search for "id:1234" or "status:foo" would not look at labels.
+RESERVED_PREFIXES = [
+    'id', 'project', 'reporter', 'summary', 'status', 'owner', 'cc',
+    'attachments', 'attachment', 'component', 'opened', 'closed',
+    'modified', 'is', 'has', 'blockedon', 'blocking', 'blocked', 'mergedinto',
+    'stars', 'starredby', 'description', 'comment', 'commentby', 'label',
+    'hotlist', 'rank', 'explicit_status', 'derived_status', 'explicit_owner',
+    'derived_owner', 'explicit_cc', 'derived_cc', 'explicit_label',
+    'derived_label', 'last_comment_by', 'exact_component',
+    'explicit_component', 'derived_component', 'alllabels', 'gate']
+
+# Suffix of a column name for an approval's approvers.
+APPROVER_COL_SUFFIX = '-approver'
+APPROVAL_SETTER_COL_SUFFIX = '-setter'
+APPROVAL_SET_ON_COL_SUFFIX = '-on'
+
+# Reserved column name suffixes that field names cannot end with.
+RESERVED_COL_NAME_SUFFIXES = [
+    APPROVER_COL_SUFFIX,
+    APPROVAL_SETTER_COL_SUFFIX,
+    APPROVAL_SET_ON_COL_SUFFIX
+]
+
+# The columns are useless in the grid view, so don't offer them.
+# These are also not used in groupby in the issue list.
+NOT_USED_IN_GRID_AXES = [
+    'Summary', 'ID', 'Opened', 'Closed', 'Modified', 'Cc',
+    'OwnerModified', 'StatusModified', 'ComponentModified',
+    'OwnerLastVisit', 'AllLabels']
+
+# Issues per page in the issue list
+DEFAULT_RESULTS_PER_PAGE = 100
+
+# Search field input indicating that the user wants to
+# jump to the specified issue.
+JUMP_RE = re.compile(r'^\d+$')
+
+# Regular expression defining a single search term.
+# Used when parsing the contents of the issue search field.
+TERM_RE = re.compile(r'[-a-zA-Z0-9._]+')
+
+# Pattern used to validate component leaf names, the parts of
+# a component path between the ">" symbols.
+COMPONENT_LEAF_PATTERN = '[a-zA-Z]([-_]?[a-zA-Z0-9])+'
+
+# Regular expression used to validate new component leaf names.
+# This should never match any string with a ">" in it.
+COMPONENT_NAME_RE = re.compile(r'^%s$' % (COMPONENT_LEAF_PATTERN))
+
+# Pattern for matching a full component name, not just a single leaf.
+# Allows any number of repeating valid leaf names separated by ">" characters.
+COMPONENT_PATH_PATTERN = '%s(\>%s)*' % (
+    COMPONENT_LEAF_PATTERN, COMPONENT_LEAF_PATTERN)
+
+# Regular expression used to validate new field names.
+FIELD_NAME_RE = re.compile(r'^[a-zA-Z]([-_]?[a-zA-Z0-9])*$')
+
+# Regular expression used to validate new phase_names.
+PHASE_NAME_RE = re.compile(r'^[a-z]([-_]?[a-z0-9])*$', re.IGNORECASE)
+
+# The next few items are specifications of the defaults for project
+# issue configurations.  These are used for projects that do not have
+# their own config.
+DEFAULT_CANNED_QUERIES = [
+    # Query ID, Name, Base query ID (not used for built-in queries), conditions
+    (1, 'All issues', 0, ''),
+    (2, 'Open issues', 0, 'is:open'),
+    (3, 'Open and owned by me', 0, 'is:open owner:me'),
+    (4, 'Open and reported by me', 0, 'is:open reporter:me'),
+    (5, 'Open and starred by me', 0, 'is:open is:starred'),
+    (6, 'New issues', 0, 'status:new'),
+    (7, 'Issues to verify', 0, 'status=fixed,done'),
+    (8, 'Open with comment by me', 0, 'is:open commentby:me'),
+    ]
+
+DEFAULT_CANNED_QUERY_CONDS = {
+    query_id: cond
+    for (query_id, _name, _base, cond) in DEFAULT_CANNED_QUERIES}
+
+ALL_ISSUES_CAN = 1
+OPEN_ISSUES_CAN = 2
+
+# Define well-known issue statuses.  Each status has 3 parts: a name, a
+# description, and True if the status means that an issue should be
+# considered to be open or False if it should be considered closed.
+DEFAULT_WELL_KNOWN_STATUSES = [
+    # Name, docstring, means_open, deprecated
+    ('New', 'Issue has not had initial review yet', True, False),
+    ('Accepted', 'Problem reproduced / Need acknowledged', True, False),
+    ('Started', 'Work on this issue has begun', True, False),
+    ('Fixed', 'Developer made source code changes, QA should verify', False,
+     False),
+    ('Verified', 'QA has verified that the fix worked', False, False),
+    ('Invalid', 'This was not a valid issue report', False, False),
+    ('Duplicate', 'This report duplicates an existing issue', False, False),
+    ('WontFix', 'We decided to not take action on this issue', False, False),
+    ('Done', 'The requested non-coding task was completed', False, False),
+    ]
+
+DEFAULT_WELL_KNOWN_LABELS = [
+    # Name, docstring, deprecated
+    ('Type-Defect', 'Report of a software defect', False),
+    ('Type-Enhancement', 'Request for enhancement', False),
+    ('Type-Task', 'Work item that doesn\'t change the code or docs', False),
+    ('Type-Other', 'Some other kind of issue', False),
+    ('Priority-Critical', 'Must resolve in the specified milestone', False),
+    ('Priority-High', 'Strongly want to resolve in the specified milestone',
+        False),
+    ('Priority-Medium', 'Normal priority', False),
+    ('Priority-Low', 'Might slip to later milestone', False),
+    ('OpSys-All', 'Affects all operating systems', False),
+    ('OpSys-Windows', 'Affects Windows users', False),
+    ('OpSys-Linux', 'Affects Linux users', False),
+    ('OpSys-OSX', 'Affects Mac OS X users', False),
+    ('Milestone-Release1.0', 'All essential functionality working', False),
+    ('Security', 'Security risk to users', False),
+    ('Performance', 'Performance issue', False),
+    ('Usability', 'Affects program usability', False),
+    ('Maintainability', 'Hinders future changes', False),
+    ]
+
+# Exclusive label prefixes are ones that can only be used once per issue.
+# For example, an issue would normally have only one Priority-* label, whereas
+# an issue might have many OpSys-* labels.
+DEFAULT_EXCL_LABEL_PREFIXES = ['Type', 'Priority', 'Milestone']
+
+DEFAULT_USER_DEFECT_REPORT_TEMPLATE = {
+    'name': 'Defect report from user',
+    'summary': 'Enter one-line summary',
+    'summary_must_be_edited': True,
+    'content': (
+        'What steps will reproduce the problem?\n'
+        '1. \n'
+        '2. \n'
+        '3. \n'
+        '\n'
+        'What is the expected output?\n'
+        '\n'
+        '\n'
+        'What do you see instead?\n'
+        '\n'
+        '\n'
+        'What version of the product are you using? '
+        'On what operating system?\n'
+        '\n'
+        '\n'
+        'Please provide any additional information below.\n'),
+    'status': 'New',
+    'labels': ['Type-Defect', 'Priority-Medium'],
+    }
+
+DEFAULT_DEVELOPER_DEFECT_REPORT_TEMPLATE = {
+    'name': 'Defect report from developer',
+    'summary': 'Enter one-line summary',
+    'summary_must_be_edited': True,
+    'content': (
+        'What steps will reproduce the problem?\n'
+        '1. \n'
+        '2. \n'
+        '3. \n'
+        '\n'
+        'What is the expected output?\n'
+        '\n'
+        '\n'
+        'What do you see instead?\n'
+        '\n'
+        '\n'
+        'Please use labels and text to provide additional information.\n'),
+    'status': 'Accepted',
+    'labels': ['Type-Defect', 'Priority-Medium'],
+    'members_only': True,
+    }
+
+
+DEFAULT_TEMPLATES = [
+    DEFAULT_DEVELOPER_DEFECT_REPORT_TEMPLATE,
+    DEFAULT_USER_DEFECT_REPORT_TEMPLATE,
+    ]
+
+DEFAULT_STATUSES_OFFER_MERGE = ['Duplicate']
+
+
+# This is used by JS on the issue admin page to indicate that the user deleted
+# this template, so it should not be considered when updating the project's
+# issue config.
+DELETED_TEMPLATE_NAME = '<DELETED>'
+
+
+# This is the default maximum total bytes of files attached
+# to all the issues in a project.
+ISSUE_ATTACHMENTS_QUOTA_HARD = 50 * 1024 * 1024
+ISSUE_ATTACHMENTS_QUOTA_SOFT = ISSUE_ATTACHMENTS_QUOTA_HARD - 1 * 1024 * 1024
+
+# Default value for nav action after updating an issue.
+DEFAULT_AFTER_ISSUE_UPDATE = user_pb2.IssueUpdateNav.STAY_SAME_ISSUE
+
+# Maximum comment length to mitigate spammy comments
+MAX_COMMENT_CHARS = 50 * 1024
+MAX_SUMMARY_CHARS = 500
+
+SHORT_SUMMARY_LENGTH = 45
+
+# Number of recent commands to offer the user on the quick edit form.
+MAX_RECENT_COMMANDS = 5
+
+# These recent commands are shown if the user has no history of their own.
+DEFAULT_RECENT_COMMANDS = [
+    ('owner=me status=Accepted', "I'll handle this one."),
+    ('owner=me Priority=High status=Accepted', "I'll look into it soon."),
+    ('status=Fixed', 'The change for this is done now.'),
+    ('Type=Enhancement', 'This is an enhancement, not a defect.'),
+    ('status=Invalid', 'Please report this in a more appropriate place.'),
+    ]
+
+# Consider an issue to be a "noisy" issue if it has more than these:
+NOISY_ISSUE_COMMENT_COUNT = 100
+NOISY_ISSUE_STARRER_COUNT = 100
+
+# After a project owner edits the filter rules, we recompute the
+# derived field values in work items that each handle a chunk of
+# of this many items.
+RECOMPUTE_DERIVED_FIELDS_BLOCK_SIZE = 1000
+
+# This is the number of issues listed in the ReindexQueue table that will
+# be processed each minute.
+MAX_ISSUES_TO_REINDEX_PER_MINUTE = 1000