Single-item measure: "Right now, how strong is your desire/urge to smoke?". This single-item measure was rated on a scale of "0, not at all strong" to "100, extremely strong", so that higher scores indicate stronger smoking urges.

This 20-item scale measures positive and negative. Participants were asked to indicate how they felt in the past week, using a 5-point Likert scale ranging from 1="very slightly or not at all" to 5="extremely." Scores for 10 positive words and 10 negative words were summed separately and were reported as mean scores (not scale totals) ranging from 1-5, with lower scores indicating low (positive or negative) affect and higher scores indicating high (positive or negative) affect. The 10 items for POSITIVE (PA) affect are attentive, interested, alert, excited, enthusiastic, inspired, proud, determined, strong, and active. The 10 items for NEGATIVE (NA) affect are distressed, upset, hostile, irritable, scared, afraid, ashamed, guilty, nervous, and jittery.

This 4-item scale assesses global subjective happiness. Each question is rated on a Likert-scale of 1-7. Scale scores were reported as mean scores in this study, with higher scores indicating higher subjective happiness.

Two single-item happiness measures were used: "In the PAST WEEK, how happy have you felt?" and "How happy are you feeling RIGHT NOW?". Both items were rated on slider scales ranging from 0="not at all" to 100="extremely", such that higher scores indicate greater levels of happiness.

The 12-item Smoking Self-Efficacy Questionnaire (SEQ-12) assesses confidence to abstain from smoking when faced with internal stimuli (6 items; e.g., when I feel very anxious) and external stimuli (6 items; e.g., after a meal). Items were assessed on slider scales ranging from 0="not at all confident" to 100="extremely confident" and results are presented as mean scale scores, where higher scores indicate greater self-efficacy to abstain from smoking.

The single-item self-efficacy measure asked: "How CONFIDENT are you that you will be able to quit smoking/stay quit?" This item was measured on a slider scale ranging from 0="not at all" to 100="extremely confident", so that higher scores indicate greater confidence in the ability to quit smoking or stay quit.

The single-item self-efficacy measure asked: "How MOTIVATED are you to quit smoking/ stay quit?" This item was measured on a slider scale ranging from 0="not at all" to 100="extremely motivated", where higher scores indicate a greater motivation to quit smoking or stay quit.

The 18-item Attitudes Towards Smoking (ATS-18) scale measures attitudes towards smoking in current and former cigarette smokers. It was rated on a 5-point Likert scale, from 1="strongly disagree" to 5="strongly agree.". The ATS-18 has 3 sub-scales: Adverse effects of smoking (items 1-10), psychoactive benefits of smoking (items 11-14), and pleasure of smoking (items 15-18). To score, all items per sub-scale were averaged to obtain a mean score within each sub-scale. For each sub-scale, higher scores indicate greater agreement with the specific attitude towards smoking.

The Commitment to Quitting Smoking Scale (CQSS) asks participants to rate their level of agreement (Likert scale, 1="strongly disagree" to 5="strongly agree") on 8-items assessing motivation to quit smoking (e.g., I'm not going to let anything get in the way of my quitting smoking).

Scale scores are reported as the average of all items, where higher scores indicate a greater commitment to quitting smoking.

This 6-item form assesses the personal importance people place on positive and negative smoking expectancies. Items were rated on slider scales ranging from 0="not at all important" to 100="extremely important." Two sub-scale mean scores were calculated: positive expectancies (3 items), and negative smoking expectancies (3 items). On both scales, higher scores indicate a greater importance of the smoking expectancies (positive or negative).

Two single-item measures assessed the pros and cons of being smoke-free: (1) "Think about all the things you LIKE/LOVE about quitting/being smoke-free; taken together, how important are those things to you RIGHT NOW?" and (2) "Think about all the things you DISLIKE/HATE about quitting/being smoke-free; taken together, how important are those things to you RIGHT NOW?" Both single-item measures were rated on slider scales ranging from 0="not at all" to 100="extremely important", so that higher scores indicate a greater perceived importance of the pros and cons of being smoke-free, respectively.

This 10-item scale assesses perceived stress during the past month. Items were rated on a 5-point Likert scale ranging from 0="Never" to 4="Very Often." The overall scale score is the total of all 10 items, of which 4 are reverse-coded, so that score totals can range from 0 to 40 with higher scores indicating greater levels of perceived stress. The PSS has two sub-scales that assess perceived helplessness (6 items) and perceived self-efficacy (4 items). Sub-scale scores were calculated as mean scores of all sub-scale items (sub-scale score ranges: 0-4), so that higher scores on the sub-scales indicate higher perceived helplessness or higher perceived self-efficacy, respectively.

This 28-item scale assesses the use of 14 coping mechanisms. Each item was rated on a 4-point Likert-scale, where 1="I haven't been doing this at all", 2="I've been doing this a little bit", 3="I've been doing this a medium amount", and 4="I've been doing this a lot." Sub-scales consist of 2 items for each of 14 coping mechanisms with no reversals of coding: (1) Self-distraction, (2) active coping, (3) denial, (4) substance use, (5) use of emotional support, (6) use of instrumental support, (7) behavioral disengagement, (8) venting, (9) positive reframing, (10) planning, (11) humor, (12) acceptance, (13) religion, (14) self-blame. Sub-scale scores range from 2 to 8 with higher scores indicating more frequent use of each specific coping mechanism, regardless of whether they are considered adaptive or maladaptive.

self-reported gender ("What is your gender?", answer options: male, female, other)

This 10-item scale assesses overall nicotine dependence, craving, and smoking withdrawal symptoms. Items were rated on a 7-point Likert-scale ranging from 1=Strongly disagree to 7=Strongly agree. We presented mean instead of total scores for ease in interpretation, so that scale scores can range from 1.0 to 7.0, with higher scores indicating greater smoking urges.

Some participants had missing data for follow-up time-points. In the statistical analysis, we used hierarchical linear mixed models with maximum likelihood estimation to handle missing data.

Single-item measure: "Right now, how strong is your desire/urge to smoke?". This single-item measure was rated on a scale of "0, not at all strong" to "100, extremely strong", so that higher scores indicate stronger smoking urges.

n=1 participants were missing baseline data for this survey; n=4 and n=6 participants had missing data at weeks 2 and 6, respectively. Data was analyzed in a hierarchical mixed model with maximum likelihood estimation to handle missing data.

This 20-item scale measures positive and negative. Participants were asked to indicate how they felt in the past week, using a 5-point Likert scale ranging from 1="very slightly or not at all" to 5="extremely." Scores for 10 positive words and 10 negative words were summed separately and were reported as mean scores (not scale totals) ranging from 1-5, with lower scores indicating low (positive or negative) affect and higher scores indicating high (positive or negative) affect. The 10 items for POSITIVE (PA) affect are attentive, interested, alert, excited, enthusiastic, inspired, proud, determined, strong, and active. The 10 items for NEGATIVE (NA) affect are distressed, upset, hostile, irritable, scared, afraid, ashamed, guilty, nervous, and jittery.

n=1 had incomplete baseline data, n=6 were missing Week 2 data, n=5 were missing Week 6 data

This 4-item scale assesses global subjective happiness. Each question is rated on a Likert-scale of 1-7. Scale scores were reported as mean scores in this study, with higher scores indicating higher subjective happiness.

n=1 had incomplete baseline data, n=6 were missing Week 2 data, n=5 were missing Week 6 data

Two single-item happiness measures were used: "In the PAST WEEK, how happy have you felt?" and "How happy are you feeling RIGHT NOW?". Both items were rated on slider scales ranging from 0="not at all" to 100="extremely", such that higher scores indicate greater levels of happiness.

n=1 had incomplete baseline data, n=4 were missing Week 2 data, n=7 were missing Week 6 data

The 12-item Smoking Self-Efficacy Questionnaire (SEQ-12) assesses confidence to abstain from smoking when faced with internal stimuli (6 items; e.g., when I feel very anxious) and external stimuli (6 items; e.g., after a meal). Items were assessed on slider scales ranging from 0="not at all confident" to 100="extremely confident" and results are presented as mean scale scores, where higher scores indicate greater self-efficacy to abstain from smoking.

n=1 had incomplete baseline data, n=4 were missing Week 2 data, n=5 were missing Week 6 data

The single-item self-efficacy measure asked: "How CONFIDENT are you that you will be able to quit smoking/stay quit?" This item was measured on a slider scale ranging from 0="not at all" to 100="extremely confident", so that higher scores indicate greater confidence in the ability to quit smoking or stay quit.

n=1 had incomplete baseline data, n=4 were missing Week 2 data, n=5 were missing Week 6 data

The single-item self-efficacy measure asked: "How MOTIVATED are you to quit smoking/ stay quit?" This item was measured on a slider scale ranging from 0="not at all" to 100="extremely motivated", where higher scores indicate a greater motivation to quit smoking or stay quit.

n=4 were missing Week 2 data, n=5 were missing Week 6 data

The 18-item Attitudes Towards Smoking (ATS-18) scale measures attitudes towards smoking in current and former cigarette smokers. It was rated on a 5-point Likert scale, from 1="strongly disagree" to 5="strongly agree.". The ATS-18 has 3 sub-scales: Adverse effects of smoking (items 1-10), psychoactive benefits of smoking (items 11-14), and pleasure of smoking (items 15-18). To score, all items per sub-scale were averaged to obtain a mean score within each sub-scale. For each sub-scale, higher scores indicate greater agreement with the specific attitude towards smoking.

n=1 had incomplete baseline data, n=4 were missing Week 2 data, n=5 were missing Week 6 data

The Commitment to Quitting Smoking Scale (CQSS) asks participants to rate their level of agreement (Likert scale, 1="strongly disagree" to 5="strongly agree") on 8-items assessing motivation to quit smoking (e.g., I'm not going to let anything get in the way of my quitting smoking).

Scale scores are reported as the average of all items, where higher scores indicate a greater commitment to quitting smoking.

n=1 had incomplete baseline data, n=4 were missing Week 2 data, n=5 were missing Week 6 data

This 6-item form assesses the personal importance people place on positive and negative smoking expectancies. Items were rated on slider scales ranging from 0="not at all important" to 100="extremely important." Two sub-scale mean scores were calculated: positive expectancies (3 items), and negative smoking expectancies (3 items). On both scales, higher scores indicate a greater importance of the smoking expectancies (positive or negative).

n=4 were missing Week 2 data, n=5 were missing Week 6 data

Two single-item measures assessed the pros and cons of being smoke-free: (1) "Think about all the things you LIKE/LOVE about quitting/being smoke-free; taken together, how important are those things to you RIGHT NOW?" and (2) "Think about all the things you DISLIKE/HATE about quitting/being smoke-free; taken together, how important are those things to you RIGHT NOW?" Both single-item measures were rated on slider scales ranging from 0="not at all" to 100="extremely important", so that higher scores indicate a greater perceived importance of the pros and cons of being smoke-free, respectively.

n=4 and n=5 participants had missing data at weeks 2 and 6, respectively. Data was analyzed in a hierarchical mixed model with maximum likelihood estimation to handle missing data.

This 10-item scale assesses perceived stress during the past month. Items were rated on a 5-point Likert scale ranging from 0="Never" to 4="Very Often." The overall scale score is the total of all 10 items, of which 4 are reverse-coded, so that score totals can range from 0 to 40 with higher scores indicating greater levels of perceived stress. The PSS has two sub-scales that assess perceived helplessness (6 items) and perceived self-efficacy (4 items). Sub-scale scores were calculated as mean scores of all sub-scale items (sub-scale score ranges: 0-4), so that higher scores on the sub-scales indicate higher perceived helplessness or higher perceived self-efficacy, respectively.

n=4 were missing Week 2 data, n=5 were missing Week 6 data

This 28-item scale assesses the use of 14 coping mechanisms. Each item was rated on a 4-point Likert-scale, where 1="I haven't been doing this at all", 2="I've been doing this a little bit", 3="I've been doing this a medium amount", and 4="I've been doing this a lot." Sub-scales consist of 2 items for each of 14 coping mechanisms with no reversals of coding: (1) Self-distraction, (2) active coping, (3) denial, (4) substance use, (5) use of emotional support, (6) use of instrumental support, (7) behavioral disengagement, (8) venting, (9) positive reframing, (10) planning, (11) humor, (12) acceptance, (13) religion, (14) self-blame. Sub-scale scores range from 2 to 8 with higher scores indicating more frequent use of each specific coping mechanism, regardless of whether they are considered adaptive or maladaptive.

n=1 had incomplete baseline data for Brief COPE - Acceptance and Brief COPE denial - Baseline, n=4 were missing Week 2 data (with n=5 incomplete for Brief COPE use of emotional support, Brief COPE use of instrumental support, Brief COPE planning, Brief COPE self-blame), n=5 has incomplete baseline date (with n=6 incomplete for Brief COPE religion, Brief COPE active coping, Brief COPE Self-distraction).

App usage, as quantified by the number of days of used during the prescribed period of app use (i.e., 49), based on passively recorded app usage patterns.

Participants were asked "Have you been abstinent during the past 30 days?" in follow-up to providing their current smoking status as "I do not smoke at all." The outcome is presented as a % of participants who self-reported 30-day point-prevalence smoking abstinence. Participants were assumed to be smoking if they did not complete surveys.

ATS - Pleasure

The a priori threshold for statistical significance was alpha=.05. We did not adjust for multiple comparisons, because this was a secondary outcome. The p-value is for a planned specific comparison of week 6 to baseline.